Legacy ImageMagick Discussions Archive

I am wondering this as well. Did you find a solution?

Thanks again snibgo, I got it working with defineValue.

a) Is there function in Magick++ to apply desired chroma subsampling factor (like the command line "-sampling-factor")?
b) Further, I understand that by default, when writing jpeg images, 4:2:0 subsampling will be applied by default up to quality factor 90; above 90, no subsampling will occur by ...

Hello, I think I found a bug. It could be attributed to user error, but I think I've ruled out that possibility.
The problem is in supplying a "quantization-table.xml" I wish to encode with the following QTs in a C++ program:
Luminance Quantization Table
16, 12, 14, 17, 22, 30, 45, 72,
12, 13, 14 ...

Anyone out there know how I can fix this and encode with the desired QTs?

I can't get it to work out.
I am using the imagemagick supplied "quantization-table.xml" that will encode with the following QTs:
Luminance Quantization Table
16, 12, 14, 17, 22, 30, 45, 72,
12, 13, 14, 17, 22, 31, 46, 74,
14, 14, 16, 19, 25, 35, 52, 83,
17, 17, 19, 23, 30, 41, 62, 100,
22, 22 ...

Yes, this should do it. I'll work with it.
Thanks, Jeff

Hello, I'm working on a C++ application and want to compress with custom quantization tables. Is there a way to do this in a C++ program? The "quality factor" function is not precise enough. And I know I can do this with the command line installation of ImageMagick but I can't find the solution for ...