| | <<<Back 1 day (to 2019/04/02) | 20190403 |
| i3v | +ray_laptop: Thanks for your reply! | 01:09.30 |
| | > your question is probably best handled by mvrhel | 01:09.38 |
| | That would be very if he would shed some light on this... | 01:09.57 |
| | Concerning the "-dUseFastColor=true": | 01:10.03 |
| | 1) Indeed, the conversion formula based on "255 minus RGB" looks very attractive in the sense of that there should be no clipping. | 01:10.14 |
| | 2) However, although it works for `-sDEVICE=tiff32nc` it seem to be ignored for `-sDEVICE=pdfwrite` in gs9.26 . Also, this switch is not mentioned in https://www.ghostscript.com/doc/9.26/VectorDevices.htm . | 01:10.23 |
| | Thus, AFAIU, it is not related to pdf. (And I'm still assuming we're in the context of https://bugs.ghostscript.com/show_bug.cgi?id=700931 , which is about pdfwrite.) | 01:10.35 |
| | @kens: | 01:10.48 |
| | > whn we get RGB and CMYK inputs from an input source these are uncharacterised sources. They are not 'DefaultRGB' or 'DefaultCMYK' which have a soecific meaning in PDF terms. | 01:11.08 |
| | Hm... My assumption was based on that https://www.ghostscript.com/doc/9.26/VectorDevices.htm#PDFX says: | 01:11.18 |
| | > DeviceRGB color space is substituted with the DefaultRGB color space, which must be defined in the ColorSpace category | 01:11.26 |
| | (The "DefaultRGB" is mentioned 7 times in that doc. Do you mean that info is outdated?) | 01:11.35 |
| | > You can, of course, use a different set of profiles to map from Device space into device-independent colour space. | 01:11.52 |
| | Indeed, if I add "-sDefaultRGBProfile=rgb_source_green.icc" all RGB become green. | 01:11.59 |
| | > A link is generated from the input ICC profile to the output ICC profile | 01:12.12 |
| | This sounds reasonable, but... What specific output ICC profile (and intent) is used here? Is it hardcoded to "default_cmyk"? | 01:12.20 |
| | The "-sOutputICCProfile" looked like a switch for just that, but since the | 01:12.45 |
| | http://git.ghostscript.com/?p=ghostpdl.git;a=blobdiff;f=doc/VectorDevices.htm;h=212b0b7017b728935c34aa04ddc1e47c153a92af;hp=de3fa23a6907679629f1530e38f6f2376be770f9;hb=b987c511229ba0b70e6a7691366d530fa8db7444;hpb=f5bd9757cffeb8b173cdde161b39abd381e325c3 | 01:12.55 |
| | it is completely gone from the VectorDevices.htm . | 01:13.05 |
| kens | i3v DefaultRGB is present in the input of a PDF file (that's what I mean when I say it has a specific meaning in PDF). You really are not providing enough information when you ask questions. What you said was 'When you do DeviceRGB to DeviceCMYK RGB lives in the DefaultRGB space'. That's a general question about RGB to CMYK conversion, not a question regarding PDF/X3 conversions. | 07:23.11 |
| | If you want to discuss a specific context then you really need to let me know what that context is, otherwise I'm just going to assume hte most general case | 07:23.42 |
| | Inoring the PDFX-3 question and speaking specifically about general RGB to CMYK conversion; the RGB components are mapped into device-independent colour space using the defaul RGB RGB profile (as mentioned), the device independent colours are then mapped back to CMYK using the CMYK default profile I believe, though I would have to do some investigation to check this. No we don't use the OutputICCProfile in pdfwrite. | 07:26.33 |
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