Tiff images compressed with LZW are first decompressed and then
recompressed with flate compression. This takes a lot of memory and
time. Jpeg images are included as-is with any decompression/compression.
Paulo
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of Pierre Jourdan
> Sent: Wednesday, May 23, 2007 1:52 PM
> To: [email protected]
> Subject: Re: [iText-questions] performance of tiff
> implementation in itext
>
> I was profiling my application that creates a pdf from multiple files
>
>
> (pdf, jpeg, tiff) using iText2.0.1 and I saw that
> lots of memory and cpu are spent in :
>
> com.lowagie.text.pdf.codec.TIFFLZWDecoder.initializeStringTable
>
> com.lowagie.text.pdf.codec.TIFFLZWDecoder.addStringToTable
> com.lowagie.text.pdf.codec.TiffImage.getTiffImageColor
>
> those allocates many byte Arrays.
>
>
>
> It does what is needed to read the image.
>
>
> Yes, but regarding jpeg or other pdf, tiff decoding requires
> two or three times more memory for same size of source file
> and much more cpu.
> But anyway I have no knowledge in Tiff specifications ; hence
> it mays be just the Tiff format which is a mess and not
> targeted for performance in reading.
>
>
> > Just wondering if there are some ways to improve this
> Tiff codec ?
> Sure, code contributions are always welcome. You may
> also use smaller
>
> images, that will take less memory. This question is in
> line with those
> questions "I create a PDF with 50000 pages and it need
> a lot of memory
> and time, why?".
>
>
> It was not the meaning. Just asking why it takes so much more
> memory and cpu to decode a tiff image, compare to a jpeg
> image (for same size of course)
> and if someone knows already a way to improve that. (like
> first convert the image with another library or use a
> specific iText class that just copy the tiff inside the pdf
> without decoding it).
>
> Notes: my tests are made on tiff images of 2Mo, color 24
> bits, RGB, compression LZW, 1010x1294.
> But yes, I know it's an open-source project and I'm not
> asking the author to work on that right now; don't get upset
> please ;o)
>
> Pierre
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