Evaluate ImageMagick comparison and its different metrics

[nuest]

ImageMagick has different metrics to calculate differences between images: https://www.imagemagick.org/script/command-line-options.php#metric

Might be able to get this running in node and should compare it to our current metrics based on blink-diff: https://www.npmjs.com/search?q=magick&ranking=popularity

The function is also easily available in R via magick: https://rdrr.io/cran/magick/man/analysis.html - thanks to @jeroen for the pointer!

library(magick)

> image1 <- image_read("~/Desktop/index1.png")
> image2 <- image_read("~/Desktop/index2.png")
> print(image1)
  format width height colorspace matte filesize density
1    PNG  1344    960       sRGB FALSE    84130   76x76
> image_compare_dist(image1, image2)
$distortion
[1] 0.9503712

> image_compare(image1, image2)
  format width height colorspace matte filesize density
1    PNG  1344    960       sRGB  TRUE        0   76x76
> image_compare(image1, image2, fuzz = 5)
  format width height colorspace matte filesize density
1    PNG  1344    960       sRGB  TRUE        0   76x76
> image_compare(image1, image2, fuzz = 50)
  format width height colorspace matte filesize density
1    PNG  1344    960       sRGB  TRUE        0   76x76
> image_compare_dist(image1, image2, fuzz = 50)
$distortion
[1] 0.9503712

> image_compare_dist(image1, image2, metric = "phash")
$distortion
[1] 0.2836806

> image_compare(image1, image2, metric = "phash")
  format width height colorspace matte filesize density
1    PNG  1344    960       sRGB  TRUE        0   76x76

It has similar challenges though, but the numeric metric could help and be more effective than the current "pixel counting".

• build a test case where the line in the plot differs and has the exact same distortion number than a plot where only the font introduces errors

> metric_types()
 [1] "Undefined" "AE"        "Fuzz"      "MAE"       "MEPP"      "MSE"       "NCC"      
 [8] "PAE"       "PHASH"     "PSNR"      "RMSE"
> image_compare_dist(image1, image2, metric = "PAE")
$distortion
[1] 1

> image_compare_dist(image1, image2, metric = "PSNR")
$distortion
[1] 25.01049

> image_compare_dist(image1, image2, metric = "MEPP")
$distortion
[1] 1329365910

The different metrics give different output numbers, but the image is not perceivably different.

Used images for testing: