Legacy ImageMagick Discussions Archive

Hello,

I did search the forum but did not find a solution to this, or overlooked it. I am resisizing some PNG images and getting obscene file sizes for some of the output (smaller resolution) images. The command I'm using is:

convert > [original file] -resize '400' -strip -quality 90 -unsharp 4.5x.5 [output file]

An example of results:

Original file: 582 x 800 : 58.6KB : 1027 colors

Resize 1: 400 x 550 : 304KB : 3161 colors
Resize 2: 73 x 100 : 31KB : 550 colors

Any help would be appreciated. This is killing me!

It would help us if you posted the images (put them on the web somewhere and tell us the URLs).

I would expect sharpening to increase the sizes.

Sure thing:

Original: http://www.freestockphotos.biz/download ... /11440.png

Resize 1: http://www.freestockphotos.biz/pictures ... 40/egg.png (slightly smaller dimensions, much higher file size)
Resize 2: http://www.freestockphotos.biz/thumbs_0 ... _11440.png (much smaller dimensions, somewhat smaller, but still larger than expected file size)

IM does not necessarily make optimized size pngs. Also be sure you are using -quality correctly. see http://www.imagemagick.org/Usage/formats/#png_quality and http://www.imagemagick.org/Usage/formats/#png_non-im

Thanks fmw42,

I did read up on the -quality for pngs after I originally posted, and did quite a few tests without any significant results. I will look at some of the other optimizer possibilities, but not sure if they'll be available for me to use.

What version IM do you use, on what platform? Your commands on IM 6.6.0-8 Q16 Windows 7 gives egg.png as 69785 bytes. Partly because it outputs 8-bit channels, not 16-bit.

If on Q16, add -depth 8 to generate 8 bits per channel rather than 16 bits per channel. Also see PNG8: vs PNG32: and PNG24 http://www.imagemagick.org/Usage/formats/#png_formats and png controls at http://www.imagemagick.org/Usage/formats/#png_write

It looks like I am using version: 6.3.9 12/10/08 Q16

I will have to talk to my web host to see about updating the version.

I will try -depth and do the reading up. Thank you for your help so far, I appreciate it!