Joined: 29 Jan 2009 Posts: 411 Location: UK
Posted: Mon 17 Oct 2016, 21:05 Post subject:
Image reduce and convert Subject description: Tools to change image depth, size
Greetings forum readers:
My attempts to post a few programs I have compiled recently:
The best tool to my knowledge to convert 24 bit RGB(A) png images to 8-bit palette. (The second best in my experience is the GIMP). The GIMP also has a posterize tool that can reduce colors to more than 256 whereas pngquant's maximum is 256. pngquant offers the choice of dithering and the number of colours in the final image. For example choose 15 colours for a 4 bit palette, 7 for a 3 bit palette etc for big filesize reduction.
Mostly I use as a commandline to resize images. Has various other options to change colourspace, dithering and so on.
Why awk? Smaller than Perl, is typically configured with busybox so near universal availability. The version of awk known as mawk posted elesewhere in this forum is by a few magnitudes faster than a shell script. mawk does not support IGNORECASE=1 so the case insensitive index function was included so that mawk can be used.
partinfo.awk relies on the output of fdisk and blkid to list the sd device partitions, their partition filetypes and labels if any. Some versions of blkid do not output the filesystem type so this awk script will not work as intended on some systems.
pngquant and imageworsen (imagew) were compiled on upup-raring and should work on most fairly recent systems not so sure about others such as wary that may use older versions for example of libpng.
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