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Tilman Hausherr edited comment on PDFBOX-4184 at 9/21/18 5:44 PM: ------------------------------------------------------------------ I did a size comparison. It went over the zip files from 0 to 18. The attachment has the files were the size of the predictor compression was at least 5% over the size of the "old" compression. Almost all of the files are jpeg files and of the kind that shouldn't have been jpeg compressed in the first place. Jpeg is for photographs and not for charts, or anything with sharp edges. was (Author: tilman): I did a size comparison. It went over the zip files from 0 to 18. The attachment has the files were the size of the predictor compression was at least 5% over the size of the "old" compression. Alsmost all of the files are jpeg files and of the kind that shouldn't have been jpeg compressed in the first place. Jpeg is for photographs and not for charts, or anything with sharp edges. > [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 > Assignee: Tilman Hausherr > 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