JP4956957B2 - Projector device and projection method - Google Patents

Description

The present invention, a projector apparatus, and a projection shadow method, and a program.

  In a projector apparatus, when an image or document input from a personal computer or the like is enlarged and projected onto a screen or the like, the original color may be reproduced on the projection surface when the projection surface such as the screen is a color other than white. For example, the projected characters may be difficult to see, or the image color may appear different from the original color.

As a method of preventing this and reproducing a color close to the original color on the projection screen, for example, as described in Patent Document 1 below, color information of a projection surface such as a screen is detected and a projected image is displayed. There is a method of adjusting the mixing amount of primary colors based on detected color information.
JP 2003-333611 A

  However, according to the above method, the color reproducibility in the projected image can be improved, but this has its own limitations. Further, when a document or the like created by a personal computer is projected, it is general that the majority of the projected area is a character background (ground) portion. For this reason, even if the above method is used, the visibility of characters is low when a document is projected, and particularly when the projection surface is a dark color (low light reflectance), the visibility is significantly reduced. There was a problem.

The present invention, such conventional has been made in view of the problems, a projector apparatus which makes it possible to improve the visibility of the character at the time of the projection of the document, and aims to provide a projection shadow method, and program To do.

In order to solve the above-mentioned problem, in the invention of claim 1, in the projector apparatus that projects and displays an image based on an input signal on an arbitrary projection plane, the input in a state displayed on the arbitrary projection plane Contrast detection means for detecting the contrast value of the image based on the signal, inspection conversion means for sequentially converting the color of the character included in the image into a plurality of inspection colors during the inspection projection period, and this inspection conversion means Each time the color of the character is sequentially converted, the storage means stores the contrast value detected by the contrast detection means in association with the inspection color being converted, and after the end of the inspection projection period, by converting the test color highest contrast value stored in the storage means the color of characters contained in the image corresponding the color of characters contained in the image It was that and a first color conversion means for converting the predetermined color different from the original color based on the input signal.

According to a second aspect of the present invention, the first color converting means is different from the original color based on the input signal, in addition to the character color included in the image, the background color of the character. At the same time, it was converted to a color corresponding to the difference in character color after conversion.
In the invention of claim 3, the inspection conversion means sequentially converts the character background color together with the character color included in the image into a plurality of inspection colors during the inspection projection period, The storage unit stores the contrast value detected by the contrast detection unit in association with the inspection color being converted each time the character color and the background color of the character are sequentially converted by the inspection conversion unit. The first color conversion means corresponds to the highest contrast value stored in the storage means for the background color of the character together with the color of the character included in the image after the end of the inspection projection period. It was supposed to be converted to inspection color.

According to a fourth aspect of the invention, there is provided character detection means for detecting a character portion included in the image based on the input signal, and the first color conversion means in the previous period is the character detected by the character detection means. The color of the portion is converted to the inspection color corresponding to the highest contrast value stored in the storage means .
Further, in the invention of claim 5, there is further provided recognition means for recognizing whether or not the inputted input signal is document data, and the recognition means recognizes that the input signal is document data. The first color conversion unit converts the character color included in the image into an inspection color corresponding to the highest contrast value stored in the storage unit .
According to a sixth aspect of the present invention, the projector includes a plurality of projection modes, and the first color is selected when a first projection mode is selected from the plurality of projection modes by a user. conversion means, after the end of the previous SL projection period for inspection, which the highest contrast value with the color of the text color of a character background stored in the storage means included in the image is converted into a test colors corresponding It was.
Further, in the invention of claim 7, when a second projection mode different from the first projection mode is selected from the plurality of projection modes by the user, the color of the character included in the image At the same time, it further includes second color conversion means for converting the color of the character included in the image into a predetermined color different from the original color based on the input signal by inverting the background color of the character.
According to the invention of claim 8, in the projector device for projecting and displaying an image based on the input signal on an arbitrary projection plane, the thickness of the character included in the image is changed to the original thickness based on the input signal. Thickness conversion means for increasing the thickness was provided.

According to a ninth aspect of the invention, there is provided a method for projecting an image in a projector device that projects an image based on an input signal onto an arbitrary projection plane and displays the image on the arbitrary projection plane, wherein the image is displayed on the arbitrary projection plane. A contrast detecting step for detecting a contrast value of the image based on the input signal, an inspection conversion step for sequentially converting a character color included in the image into a plurality of inspection colors during the inspection projection period, and the inspection A storage step of storing the contrast value detected by the contrast detection unit in association with the inspection color being converted each time the character color is sequentially converted by the conversion unit; and the end of the inspection projection period later, by the highest contrast value the color of characters contained in the image stored in said storage means into a test color corresponding the picture A first color conversion step of converting a predetermined color different from the original color of the color of the character based on the input signal contained in a process which includes a.

In the invention of claim 10 , the input signal in a state where the computer having the projector device that projects and displays an image based on the input signal on an arbitrary projection plane is displayed on the arbitrary projection plane. Contrast detecting means for detecting the contrast value of the image based on the above, inspection converting means for sequentially converting the color of the character included in the image into a plurality of inspection colors in the projection period for inspection, and the inspection converting means Storage means for storing the contrast value detected by the contrast detection means in association with the inspection color being converted each time the colors are sequentially converted, and included in the image after the end of the inspection projection period by the highest contrast value the color of the text stored in the storage means into a test color corresponding, the color of characters contained in the image And a program for the original color based on the force signal to function as the first color conversion means for converting different predetermined color.

In the present invention, as described above, it is possible to improve the character of visibility at the time of the projection of the document.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram showing an electrical configuration of projector apparatus 1 according to the first embodiment of the present invention.

  The projector device 1 is provided in a main body (not shown), and for example, a USB terminal for video input / output connection with an external device such as a personal computer, a mini-D-SUB terminal for video input, an S terminal, an RCA terminal, and the like. An input / output connector portion 2 is provided.

  Input signals such as document data and image signals of various standards input from the input / output connector unit 2 are input to the image conversion unit 4 via the input / output interface (I / F) 3 and the system bus SB. And then sent to the projection encoder 5. The projection encoder 5 develops and stores the transmitted image signal in the video RAM 6, generates a video signal from the stored contents of the video RAM 6, and outputs the video signal to the projection drive unit 7.

  The projection drive unit 7 drives the spatial light modulation element (SOM) 8 to display at a predetermined frame rate (for example, 30 frames / second) corresponding to the transmitted image signal. Then, by irradiating the spatial light modulation element 8 with light emitted from the light source unit 9 made of, for example, a reflector or a light source lamp, an optical image is formed with the reflected light, and this causes the projection lens 10 to And projected on an arbitrary projection plane 100. The projection lens 10 is composed of a lens group having zoom (magnification) and focus adjustment functions, and is driven by the lens motor 11 so that the zoom position and the focus position are appropriately adjusted.

  On the other hand, the operation of each unit of the projector device 1 is controlled by the control unit 12. The control unit 12 is a color conversion unit and a color determination unit of the present invention, and is mainly used as a CPU, a ROM 12a in which a CPU and a program necessary for controlling each unit and various data are fixedly stored, and a work memory. The ROM 12a includes a program for causing the CPU to perform an operation described later, character font (typeface data), and data constituting a color determination table T (see FIG. 2) described later. It is remembered.

  In addition to the input / output interface 3, the image conversion unit 4, and the projection encoder 5 described above, the display drive unit 13 and the color detection unit 15 are connected to the control unit 12 via the system bus SB. The display drive unit 13 drives the display unit 14 configured by a liquid crystal display panel according to a command from the control unit 12 and causes the display unit 14 to display an operation state of the apparatus, various guide messages, and the like.

  The color detection unit 15 includes a color detection sensor that detects color information of the projection surface 100 on which the projector device 1 displays a projection image, an amplifier that amplifies the detection signal of the color detection sensor, and the detection signal after amplification is converted into a digital signal. It comprises an A / D converter for conversion, and outputs the detection result to the control unit 12. In the present embodiment, the color detection sensor is an RGB sensor composed of a plurality of optical sensors that use filters to separate light into three colors of RGB and detect brightness for each color. In addition to this, for example, a solid-state imaging device (color CCD or the like) provided with a color filter is used as the color detection sensor as long as it can detect color information of the projection area of the projection image on the projection plane 100. be able to. The projector apparatus 1 is an optical system that is disposed in the vicinity of the projection lens 10 in an apparatus main body (not shown), and that allows the color detection sensor to detect color information in the projection area of the projection image on the projection plane 100. 16 is provided.

  Further, a key input unit 17 is connected to the control unit 12. The key input unit 17 includes various operation buttons including a power button that is used by the user to operate the projector device 1, and an operation signal indicating the operation content according to the operation of any one of the operation buttons or the like is sent to the control unit 12. input.

  FIG. 2 is a conceptual diagram showing the color determination table T described above. The color determination table T includes character colors (txt-C1, txt-C2,... Txt-) corresponding to a plurality of predetermined detection colors (scr-C1, scr-C2,... Scr-Cn). Cn) and a background color (bgd-C1, bgd-C2,... Bgd-Cn). Here, the detected color is the color of the projection plane 100 that can be detected by the color detection unit 15, and the character color and the background color are projected on the projection plane 100 when a character is projected onto the projection plane 100 of a certain color. It is a combination color that increases the contrast (difference between brightness and darkness) between the character and the background, and is the display character color and background color. For example, for the detection color that is a blackboard color (black, dark green, etc.), white is set as the character color and black is set as the background color.

  In the projector apparatus 1, three types of projection modes, ie, a normal mode, an automatic mode, and a blackboard mode are prepared as projection modes, and the user can selectively set one of the projection modes. The blackboard mode is a projection mode provided on the premise that the blackboard mode is used when projecting on the blackboard.

  Next, an operation according to the present invention of the projector apparatus 1 having the above configuration will be described. FIG. 3 is a flowchart showing the contents of processing executed by the control unit 12 after power-on.

  After starting the operation upon power-on or the like, the control unit 12 checks whether or not the input signal input from the input / output connector unit 2 is document data. If the input signal is not document data (NO in step SA1), Immediately project an image based on the input signal (step SA6). Further, even when the input signal is document data (YES in step SA1) and the projection mode at that time is the normal mode (both steps SA2 and SA4 are NO), it is immediately based on the input signal (document data). An image is projected (step SA6).

  On the other hand, if the input signal is document data (YES at step SA1), if the projection mode is the automatic mode (YES at step SA2), the automatic conversion process of FIG. 4 is executed (step SA3). An image based on the document data after the processing is projected (step SA6), and if the projection mode is the blackboard mode (NO in step SA2 and YES in step SA4), the blackboard conversion process of FIG. 5 is performed ( In step SA5), an image based on the document data after such processing is projected (step SA6).

  As shown in FIG. 4, in the automatic conversion process, for example, a white image having a predetermined luminance is generated and projected, and the color detection unit 15 performs color information (brightness for each RGB color) on the projection plane 100. ) Is detected (step SB1), and the color of the projection plane 100 is determined based on the detection result (step SB2). Next, after obtaining the display character color and background color corresponding to the determined color from the color determination table T (see FIG. 2) described above (step SB3), the character color and background color in the document data are confirmed. (Step SB4).

  If both the confirmed character color and background color match the display character color and background color obtained from the color determination table T (YES in both steps SB5 and SB7), do nothing. First, the automatic conversion process is terminated and the process returns to the main flow of FIG.

  On the other hand, if the confirmed character color is different from the display character color (NO in step SB5), the character color in the document data is converted to the display character color (step SB6), and the confirmed background color. Is different from the display background color (NO in step SB7), the background color in the document data is converted to the display background color (step SB8), and the process returns to the main flow of FIG. In other words, in the automatic conversion process, the character color and the background color in the input document data are always converted into a combination color corresponding to the color of the projection plane 100 and having the maximum contrast between the character and the background. I do.

  As a result, in step SA6 described above, a document with a high character visibility is displayed on the projection plane 100. FIG. 6 shows that when the color of the projection plane 100 is “scr-C1”, the character color is converted to “txt-C1” and the background color is converted to “bgd-C1” in accordance with the automatic conversion process described above. , Between the projection state (a) of the document projected on the projection surface 100 and the projection state (b) of the document when projected on the projection surface 100 in the normal mode without automatic conversion processing. It is the figure which showed the difference in visibility for convenience.

  Next, the blackboard conversion process described above will be described. As shown in FIG. 5, in the blackboard conversion process, first, the character color and background color in the document data are confirmed (step SC1). If the background color is white and the character color is black (YES in step SC2), the character color and the background color are reversed. That is, the character color is converted to white and the background color is converted to black (step SC3). Further, the character font being used is confirmed (step SC4). If it is not a bold font (NO in step SC5), the character font is converted into a bold font (step SC6), and then the character font shown in FIG. Return to the main flow. If the background color in the document data is white and the character color is not black (NO in step SC2), the processing is not performed in step SC3, and the font used is already bold. If YES (YES in step SC2), the blackboard conversion process is terminated without performing the process of step SC6, and the process returns to the main flow of FIG.

  As a result, in step SA6 described above, for example, as shown in FIG. 7A, a document based on general document data with a white background color and a black character color is projected onto a blackboard (including a green one). At this time, as shown in FIG. 8B, the contrast between the character and the background is low, that is, compared to the state when the image is projected on the projection plane 100 in the normal mode without the blackboard conversion process. As shown in a), the characters and the background are projected (displayed) on the projection plane 100 with a high contrast.

  During the projection by the above-described operation, until the input signal is changed (NO in step SA7), the projection in step SA6 is continued, and if the input signal is changed (NO in step SA7), At this point, the process returns to step SA1 to repeat the above-described processing.

  As described above, according to the present embodiment, when a document based on document data is projected, the automatic mode is selected by the user even if a large part of the projected area is the background (ground) portion of the character. If so, the combination of the character color and the background color is converted into a combination corresponding to the color of the projection plane 100 and the contrast between the character and the background is increased, whereby the document to be projected is converted to the character Can be displayed on the projection plane 100 with high visibility.

  When the blackboard mode is selected, when the text color is black and the background color is white, the text color and the background color are reversed to increase the contrast between the text and the background. By making the characters stand out by converting the characters into bold, the document to be projected can be displayed on the projection plane 100 with high visibility of the characters. Moreover, since the projection surface (blackboard) 100 is not exposed to excessive light from the background portion, characters and the like are placed on the projection surface (blackboard) 100 during projection of the document, as shown in FIG. In the case of additional writing, it becomes easy to write characters and the like. At the same time, it is possible to reduce the degree of eye fatigue when the projected image (document) is viewed for a long time.

  Here, in the present embodiment, during the projection operation, the projection operation in one of the set projection modes is repeatedly performed, but not limited thereto, the projection operation in the automatic mode or the blackboard mode, That is, the automatic conversion process (FIG. 4) or the blackboard conversion process (FIG. 5) described above may be temporarily performed only when a predetermined key operation is performed by the user, that is, only when necessary. In that case, a temporary transition to the automatic mode or the blackboard mode may be allowed only when the input signal is document data.

  In the present embodiment, the projector apparatus 1 is described in which the automatic mode and the blackboard mode are provided as the projection mode in addition to the normal mode. However, only one of the automatic mode and the blackboard mode is provided. May be. If only the blackboard mode is provided in addition to the normal mode, the color detection unit 15 and the optical system 16 and the data of the color determination table T described above are unnecessary as a matter of course.

  Further, in the color determination table T (FIG. 2) used in the automatic mode, colorless (transparent) is set for either the character color or the background color corresponding to the predetermined detection color. Also good.

  In the automatic mode, the character color and background color in the input document data are automatically converted into a combination color that maximizes the contrast between the character and the background. The color may be converted according to the color.

  In the blackboard mode, the character color and the background color are reversed only when the character color in the input document data is black and the background color is white. In the case where the combination is a combination of other colors, both colors may be inverted, or both colors may be inverted unconditionally.

  In the blackboard mode, the process of inverting the character color and background color in the input document data and the process of converting the character to bold are performed. However, only one of the processes may be performed. Good.

  In this embodiment, an automatic mode is provided in which the color of the projection plane 100 is automatically determined and the character color and the background color are converted into a combination of colors according to the color of the projection plane 100. The following may be used. For example, a predetermined key operation allows the user to select a close color that matches or resembles the color of the projection plane 100 from among a plurality of candidate colors, and the character color and the background color or only the character color corresponds to the selected color. A predetermined combination of colors determined in advance, or a projection mode for converting into a predetermined color may be provided.

Furthermore, each time a predetermined key operation is performed by the user without providing a specific projection mode, the character color and the background color are converted, and the combination is selected from a plurality of combinations (projection planes) in a predetermined order. When 100 colors are a certain color, it can be changed to a combination that increases the contrast between the character and the background), or only the character color is sequentially converted into one of a plurality of predetermined candidate colors. It is good also as a structure to do.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. FIG. 9 is a block diagram showing an electrical configuration of projector apparatus 51 according to the second embodiment of the present invention. As is apparent from the figure, the projector device 51 has a configuration in which the color detection unit 15 described above is changed to an imaging unit 52 in the projector device 1 shown in FIG.

  The imaging unit 52 is a solid-state imaging device (CCD or the like) that images the projection plane 100 on which the projector device 51 displays a projected image, and an imaging signal output from the solid-state imaging device is converted into digital image data (monochrome image data). It comprises a signal processing circuit or the like for conversion, images the projection plane 100 in accordance with an instruction from the control unit 12, and outputs image data to the control unit 12. In the present embodiment, the optical system 16 enables the imaging unit 52 to capture the projection area of the projected image on the projection plane 100.

  In the present embodiment, the ROM 12a of the control unit 12 does not store the data constituting the color determination table T described in the first embodiment, and the CPU is different from the first embodiment. A program for causing the control unit 12 to function as the inspection conversion unit and the thickness conversion unit of the present invention by performing an operation described later is stored. In the present embodiment, the RAM 12b of the control unit 12 is the storage unit of the present invention, and the imaging unit 52 and the control unit 12 constitute the contrast detection unit of the present invention. Since the configuration other than this is the same as that shown in FIG.

  Also in the projector device 51 according to the present embodiment, three types of projection modes, a normal mode, an automatic mode, and a blackboard mode, are prepared as projection modes, and the user can selectively set one of the projection modes. After the power is turned on, the control unit 12 performs the process shown in FIG. However, in step SA3 described above, automatic content conversion processing shown in FIG. 10 different from that in the first embodiment is executed.

  That is, in the automatic conversion process according to the present embodiment, first, the character color in the input document data is changed to the first inspection color among a plurality of predetermined inspection colors (step SB101), and then changed. An image based on the subsequent document data is projected (step SB102), and the image in the projected state is captured by the imaging unit 52 (step SB103). Then, a contrast value is calculated for the captured image, and the result is stored in the RAM 12b (storage means) in association with the inspection color at that time (step SB104).

  Thereafter, in step SB101, the above-described processing is repeated while sequentially changing the character color in the document data to another inspection color (NO in step SB105). After the character color is changed to the last color among the plurality of test colors and the above-described processing is completed (YES in step SB105), the character color in the input document data is stored in step SB104. The maximum contrast value is converted into the corresponding inspection color (step SB106). That is, in the automatic conversion process according to the present embodiment, a process is performed in which the character color in the input document data is converted into a color that provides the maximum contrast value when an image based on the document data is actually projected onto the projection plane 100. . Thereafter, the process returns to the main flow of FIG.

  As described above, in the present embodiment, when the automatic mode is selected by the user, when projecting a document based on the document data, most of the projected area is the background of the character (ground). Even if it is a part, the character color is a color corresponding to the color of the projection surface 100 and the contrast between the character and the background is increased, so that the document to be projected is projected with high character visibility. It can be displayed on the surface 100. The effect when the blackboard mode is selected as the projection mode is the same as in the first embodiment.

  In the automatic mode in the present embodiment, only the character color in the input document data is converted into a predetermined color so that the maximum contrast value can be obtained when an image based on the document data is actually projected onto the projection plane 100. However, not only the character color but also the background color may be combined and converted to another color. In that case, in the above-described automatic conversion process, not only the character color is sequentially changed to a plurality of inspection colors to obtain a contrast value, but also the background color is changed to a plurality of inspection colors every time the character color is changed. The contrast value may be acquired.

  Also in the present embodiment, the projection mode may be provided with only the automatic mode described above in addition to the normal mode.

  Here, in the first and second embodiments described above, the case where the automatic mode and the blackboard mode are effective projection modes only when the input signal is document data has been described. Alternatively, the following projection mode may be provided which is effective when the input signal is image data such as RGB data.

  For example, from the input image data, the character part is recognized by image recognition technology, and based on the result, either the color of the character part and / or the color of the background part is converted to another color, or the character part In addition, a projection mode may be provided in which the color of the background portion is reversed, the outline of the character portion is detected, and the detected outline is thickened, thereby converting the character into a bold character. When such a projection mode is used, when the input signal is image data such as RGB data, a document with high character visibility is displayed on the projection plane 100 as in the case of using the automatic mode or the blackboard mode. Can be displayed.

It is a block diagram of the projector apparatus which shows 1st Embodiment. It is a conceptual diagram which shows a color determination table. It is a flowchart which shows the operation | movement at the time of projection common to 1st and 2nd embodiment. It is a flowchart which shows the content of the automatic conversion process in a 1st form. It is a flowchart which shows the content of the conversion process for blackboards common to 1st and 2nd embodiment. In the 1st form, it is the figure which showed for convenience the difference in the visibility of the character at the time of projection (a) by automatic mode, and the time of projection (b) by normal mode. (A) is an example of a document based on document data, and (b) is a diagram showing a state when the document is projected in a normal mode. It is a figure which shows a state when the document of Fig.7 (a) is projected in blackboard mode. It is a block diagram of the projector apparatus which shows 2nd Embodiment. It is a flowchart which shows the content of the automatic conversion process in a 2nd form.

Explanation of symbols

1 Projector device 3 Input / output interface (I / F)
4 Image conversion unit 7 Projection drive unit 8 Spatial light modulation element (SOM)
DESCRIPTION OF SYMBOLS 12 Control part 15 Color detection part 16 Optical system 51 Projector apparatus 52 Imaging part 100 Projection surface

Claims (10)

In a projector device that projects and displays an image based on an input signal on an arbitrary projection plane,
Contrast detection means for detecting a contrast value of an image based on the input signal in a state displayed on the arbitrary projection plane;
An inspection conversion means for sequentially converting the color of the character included in the image into a plurality of inspection colors during the inspection projection period;
Storage means for storing the contrast value detected by the contrast detection means in association with the inspection color being converted each time the character color is sequentially converted by the inspection conversion means,
After the end of the inspection projection period, the character color included in the image is converted into the inspection color corresponding to the highest contrast value stored in the storage unit. First color conversion means for converting to a predetermined color different from the original color based on the input signal;
A projector apparatus comprising:   In addition to the color of the character included in the image, the first color conversion unit is configured to change the background color of the character from the original color based on the input signal and a color corresponding to the difference in the character color after conversion. The projector device according to claim 1, wherein the projector device is converted into the following. The inspection conversion means sequentially converts the character background color together with the character color included in the image into a plurality of inspection colors during the inspection projection period,
The storage unit stores the contrast value detected by the contrast detection unit in association with the inspection color being converted each time the character color and the background color of the character are sequentially converted by the inspection conversion unit. And
The first color conversion means, after the end of the inspection projection period, the character color included in the image and the background color of the character corresponding to the inspection color corresponding to the highest contrast value stored in the storage means. The projector device according to claim 1, wherein the projector device is converted into the following. Character detection means for detecting a character part included in the image based on the input signal,
The first color conversion unit converts the color of the character portion detected by the character detection unit into an inspection color corresponding to the highest contrast value stored in the storage unit. 3. The projector device according to any one of 3. Recognizing means for recognizing whether or not the input signal is document data;
When the recognition means recognizes that the input signal is document data,
5. The first color conversion unit converts the color of a character included in the image into an inspection color corresponding to the highest contrast value stored in the storage unit . 6. Projector device. The projector has a plurality of projection modes,
When the first projection mode is selected from the plurality of projection modes by the user,
It said first color converting means, after the end of the previous SL projection period for inspection, the highest contrast value with the color of the text color of a character background stored in the storage means included in the image corresponding test The projector device according to claim 1, wherein the projector device is converted into a color. When a second projection mode different from the first projection mode is selected from the plurality of projection modes by the user,
Second color conversion for converting the color of the character included in the image into a predetermined color different from the original color based on the input signal by inverting the color of the character background included in the image and the background color of the character The projector according to claim 6, further comprising means.   The projector apparatus according to claim 1, further comprising a thickness conversion unit that increases a thickness of a character included in the image to an original thickness or more based on the input signal. A method for projecting an image in a projector device that projects and displays an image based on an input signal on an arbitrary projection plane,
A contrast detection step of detecting a contrast value of an image based on the input signal in a state displayed on the arbitrary projection plane;
A test conversion step for sequentially converting the color of the characters included in the image into a plurality of test colors during the test projection period;
A storage step of storing the contrast value detected by the contrast detection unit in association with the inspection color being converted each time the character color is sequentially converted by the inspection conversion unit;
After the end of the inspection projection period, the character color included in the image is converted into the inspection color corresponding to the highest contrast value stored in the storage unit. A first color conversion step of converting to a predetermined color different from the original color based on the input signal;
A projection method characterized by comprising: A computer having a projector device that projects and displays an image based on an input signal on an arbitrary projection plane;
Contrast detection means for detecting a contrast value of an image based on the input signal in a state displayed on the arbitrary projection plane;
An inspection conversion means for sequentially converting the color of the character included in the image into a plurality of inspection colors during the inspection projection period;
Storage means for storing the contrast value detected by the contrast detection means in association with the inspection color being converted each time the character color is sequentially converted by the inspection conversion means,
After the end of the inspection projection period, the character color included in the image is converted into the inspection color corresponding to the highest contrast value stored in the storage unit. First color conversion means for converting to a predetermined color different from the original color based on the input signal;
Program to function as.

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