README.md: compare to econvert (closes: #143)

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Johannes Schauer Marin Rodrigues 2022-05-18 13:08:05 +02:00
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@ -299,3 +299,14 @@ Tesseract might not do a lossless conversion. For example it converts CMYK
input to RGB and removes the alpha channel from images with transparency. For
multipage TIFF or animated GIF, it will only convert the first frame.
Comparison to econvert from ExactImage
--------------------------------------
Like pdflatex and podofoimg2pf, econvert is able to embed JPEG images into PDF
directly without re-encoding but when given other file formats, it stores them
just using flate compressen, which unnecessarily increases the filesize.
Furthermore, it throws an error with CMYK TIF input. It also doesn't store CMYK
jpeg files as CMYK but converts them to RGB, so it's not lossless. When trying
to feed it 16bit files, it errors out with Unhandled bps/spp combination. It
also seems to choose JPEG encoding when using it on some file types (like
palette images) making it again not lossless for that input as well.