Let the PPD Generator read color spaces and color depth correctly from IPP data #5227
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…m IPP data The PPD generator did not support all combinations of color spaces and color depths when reading the information from the answer to the get-printer-attributes IPP request. especially if in Apple Raster a range of color depths is given for a color space, like "W8-16", "ADOBERGB24-48", ... Now support for a color space in any color depth is recognized and the highest depth available chosen for each color space.
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We cannot accept this pull request as-is. First, defaulting to the highest bit depth will lead to serious performance regressions. This is not something we will change our minds on - high bit depth for AdobeRGB is OK (and expected), but not for the others. Second, sRGB is only defined for 24-bit (8-bit per component). Higher bit depth sRGB is actually a different color space (scRGB, defined by HP and Microsoft) as none of the "tweaks" employed for 16-bit and 24-bit sRGB are valid for higher bit depths. scRGB never caught on and we don't support it "natively". Finally, we will consider supporting 24-bit AdobeRGB, but despite the wider gamut you lose a lot of color resolution so the results are often worse than for 24-bit sRGB. For that reason we don't actually allow 24-bit AdobeRGB with Apple Raster, but if a printer is reporting support for it we might bend the rules for that... |
Changes: If there is only one color depth offered by the printer, this depth is used, regardless whether it is 8 or 16 bit. If there are both 8 and 16 bit offered, in case of sRGB we default to 8 bit, in case of AdobeRGB to 16 bit, and in case of Grayscale two entries, one for 8 bit and one for 16 are created.
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Thanks for the info, I simply purely followed the output of the printer on get-printer-attributes and also that CUPS, cups-filters and the printer are handling the color depths correctly. |
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I have tested your change now and on my printer at least it provides the same options as my change. Thanks. |
The PPD generator did not support all combinations of color spaces and color depths when reading the information from the answer to the get-printer-attributes IPP request. especially if in Apple Raster a range of color depths is given for a color space, like "W8-16", "ADOBERGB24-48", ... Now support for a color space in any color depth is recognized and the highest depth available chosen for each color space.
On my DeskJet 2540 this was especially leading to the fact that only the standard RGB color space appeared in the "ColorModel" option and not the also supported Gray and AdobeRGB color spaces. These two color spaces also print perfectly on the printer with 16 bit color depth (with CUPS 2.3b2).
HP-DeskJet_2540-ipp-attr-ippserver.txt