[Bug 302057] Re: Reducing scale of png images usually result in bigger file size

[Andrew McCarthy]

The resize is achieved by using ImageMagick to run
    convert <originalfile> -resize <newsize> <newfile>

As noted on this page:
    http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=6245
resizing causes the image to change to 16-bit, probably from 8-bit (run "identify filename.png" at a command prompt to see). I can see why this is done - as the image is shrunk, pixels are merged and new colours created. However, this makes the file larger.

Perhaps the tool should include an option that causes the output to have the same depth as the input? The original image's depth can be determined with:
    "identify -format '%[depth]' filename.png"
which outputs a single integer.

** Changed in: nautilus-image-converter (Ubuntu)
       Status: New => Confirmed

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Reducing scale of png images usually result in bigger file size
https://bugs.launchpad.net/bugs/302057
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