Legacy ImageMagick Discussions Archive

i understand '-verbose' flag show more detailed information.


but i cant understand what's the exact meaning of numbers.


I compared two filtered images.

RMSE
red: 257.988 (0.00393665)
green: 168.317 (0.00256835)
blue: 336.056 (0.00512788)
all: 263.2 (0.00401617)

PSNR
PSNR
red: 48.0975
green: 51.8069
blue: 45.8012
all: 47.9238

MAE
red: 142.675 (0.00217708)
green: 93.7039 (0.00142983)
blue: 185.962 (0.00283761)
all: 140.78 (0.00214817)

PAE
red: 3341 (0.0509804)
green: 1799 (0.027451)
blue: 4112 (0.0627451)
all: 4112 (0.0627451)


whats the meaning of the values inside of bracket()

and why peak absoulte error shows higher than 255, two images are both 24bit png image.

When IM reads an image, it stores it in memory according to how IM was compiled: Q8, Q16, Q32 or Q64. Numbers it gives are based on that data, not the bit depth of the original file.

If you are running Q16, the maximum PAE is 65535, which you will get when one image is black and the other is white.

The number in parentheses is the first number, normalised to one. So the maximum PAE in parentheses is 1.0, for any Q-number.

As a general rule, scripts should use the number in parentheses so they will work with any Q-number.