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Emmeran Seehuber commented on PDFBOX-4184: ------------------------------------------ [~tilman] Well the checkIdent() works perfectly fine for me on Mac OS X with JDK 10.0.2. But converting between color spaces can always be lossy if you are not converting into a bigger color space (e.g. into 16 bit ProPhoto etc.), as you may e.g. get clippings when not all source color values can be mapped 1:1 into the destination color space. No idea if there is something fixed in LCMS in JDK 10.0.2 to work better than in whatever JDK you used... I want to implement a "getRawImage()" method similar to the "getImage()" method in the PDImageXObject. Directly comparing the "raw" pixel values would a allow a test which would never fail. I started a branch with some changes for that some months ago, but had no time yet to finish it... That would also be something for a new ticket. > [PATCH]: Support simple lossless compression of 16 bit RGB images > ----------------------------------------------------------------- > > Key: PDFBOX-4184 > URL: https://issues.apache.org/jira/browse/PDFBOX-4184 > Project: PDFBox > Issue Type: Improvement > Components: Writing > Affects Versions: 2.0.9 > Reporter: Emmeran Seehuber > Priority: Minor > Fix For: 2.0.12, 3.0.0 PDFBox > > Attachments: 16bit.png, LoadGovdocs.java, fix_profile_use.patch, > fix_profile_use3.patch, fix_profile_use4.patch, images.zip, > lossless_predictor_based_imageencoding.patch, > lossless_predictor_based_imageencoding_v2.patch, > lossless_predictor_based_imageencoding_v3.patch, > lossless_predictor_based_imageencoding_v4.patch, > lossless_predictor_based_imageencoding_v5.patch, > lossless_predictor_based_imageencoding_v6.patch, > pdfbox_support_16bit_image_write.patch, png16-arrow-bad-no-smask.pdf, > png16-arrow-bad.pdf, png16-arrow-good-no-mask.pdf, png16-arrow-good.pdf, > size_compare.txt > > > The attached patch add support to write 16 bit per component images > correctly. I've integrated a test for this here: > [https://github.com/rototor/pdfbox-graphics2d/commit/8bf089cb74945bd4f0f15054754f51dd5b361fe9] > It only supports 16-Bit TYPE_CUSTOM with DataType == USHORT images - but this > is what you usually get when you read a 16 bit PNG file. > This would also fix [https://github.com/danfickle/openhtmltopdf/issues/173]. > The patch is against 2.0.9, but should apply to 3.0.0 too. > There is still some room for improvements when writing lossless images, as > the images are currently not efficiently encoded. I.e. you could use PNG > encodings to get a better compression. (By adding a COSName.DECODE_PARMS with > a COSName.PREDICTOR == 15 and encoding the images as PNG). But this is > something for a later patch. It would also need another API, as there is a > tradeoff speed vs compression ratio. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@pdfbox.apache.org For additional commands, e-mail: dev-h...@pdfbox.apache.org