Legacy ImageMagick Discussions Archive

fmw42 wrote:I have modified the script to use -posterize when color reducing grayscale images. I also added a background color argument. So give this a try and see if that gets what you want.

I just finished testing the latest. Yes, it works. Thanks again for all your help and time.

I just posted a potential bug report on color quantization of grayscale images. Hi Fred, It might be of interest and germane to this problem. I was checking the number of 'colors' in a grayscale image using GIMP. I was comparing IM -colorspace Gray with GIMP desaturate. IM conversion had 251 unique...

Please clarify the issue about 8 vs 9 grayshades. Currently, the IM command -colors does not honor the exact number of colors you specify. It will not exceed the specified value, but can be less. How does this affect what you are trying to do? What I have found so far: Using the grayscale image as ...

Fred,

The one minor modification I did make was at like 365 where I changed "....blackground black...." to ....blackground blue..." which allows me to see the blackest bar of the histogram.

fmw42 wrote:What was your exact command that generated the spectrum histogram? Did you do any other pre-processing besides converting it to grayscale image? Did you reduce the number of colors?

Fred

./spectrumhist -t histogram -s lum -h 500 -m 3 -w 15 -c 14 graystarynight.jpg staroutgray.jpg

Fred,

Original, converted to greyscale, and the histogram out put sent via dropbox to you. Sorry for 3 individual e-mails and links, but that's seems to be how dropbox works.

$type" = "histogram" -a "$sort" = "lum" -t histogram -s lum output looks exactly like what I am looking for except only 8 bars. What is the "-a" for. I don't see how to apply that particular option? For the record, I'm trying to analyze some classical and...

I'm trying to use spectrumhist with greyscale images. So far I've only been able to get different bars in the histograms I generate. converted jpeg to jpeg with IM -colorspace Gray generated histograms with ./spectrumhist -t histogram -s hue -h 500 -m 3 -w 15 -c 14 grayscale.jpg outfile.jpg I know t...

Thanks Fred. I knew someone would have a solution to hand. Sorry I didn't read all you script descriptions. I'll just add numbers to the output.

I'm currently using Fred Weinhaus' spectrumhist to generate some histograms from images. Thanks Fred. Your scripts saved me a great deal of time. Now I would like to post process the output and add a vertical scale, labeled with 10,20,30....90 and 5,15,25 horizontal marks. A number line based on per...