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Not sure at this point if it can be done. But if you can help that would be awesome. Png is currently 48mb and it is the correct size for printing set as well as resolution at 300 dpi. i cannot make the size smaller or the reduce resolution, so is there a way to compress this file. I see lots of compression programs but none seem to be capable of handling such a large file. Thanks for any help.

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    You don't mention print size nor pixel dimensions. It would be nice to know why 48mb is too big, because...it ought not be. Also, the half-tone line-screen resolution. If you are printing at 133 lpi, then you can probably reduce the image such that 266ppi is enough. – Yorik Jun 9 '17 at 20:56
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    Can you post the first few lines of output from pngcheck -v file.png which might give some clues (bit depth, color type, etc.). By the way, my "pngcrush" program doesn't have any filesize limit, although it might take a long time to compress your file. – Glenn Randers-Pehrson Jun 9 '17 at 21:13
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PNG isn't a proper format for printing and generally does not contain any ppi flag. In addition, I don't believe PNG supports CMYK color.

If anything, a jpg may be more appropriate. If not tiff.

All those "compression programs" are designed for web images, because that's what the PNG format is for. They aren't geared for print images.

For print, file size (kb) is traditionally never anything to be concerned with. I mean that literally. When dealing with print images, you get the quality and color correct then save and don't even bother looking at file size. Concerning yourself with files size just means you will reduce the quality of the image.

Make certain the file is in CMYK mode and 300ppi. The save your image as a jpg with the quality set to 12. Don't use Save for Web or Export commands.. just Save As. Chances are the file size will be much smaller.

Ideally, you would save the file as a .tif and provide that a printer. However, there are some instances where providing high resolution jpgs are acceptable. I have yet to see any printer accept direct png files for reproduction.

  • If the image has transparency (one reason for using PNG over JPG), a TIFF file would definitely be much better than a JPG. Hi-res JPGs are usually accepted, but saving as a TIFF image straight off the bat will almost certainly be better—except the file size, but like you I can't see any reason why the image has to be less than 25 MB to begin with. – Janus Bahs Jacquet Jun 10 '17 at 10:53
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    Well, for print... there's no such thing as transparency.. so...... – Scott Jun 10 '17 at 13:31
  • Not in the final imposition, no; but if the image is to be overlaid on top of something else, or perhaps placed on a page with a non-white background colour, any transparent areas in the PNG that became solid whites by saving as a JPG would end up looking rather different than the original. There's no information in the question of how the image is to be printed, after all. – Janus Bahs Jacquet Jun 10 '17 at 13:37
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    Agreed, but you do realize that white means nothing, literally, on press. – Scott Jun 10 '17 at 13:48

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