Legacy ImageMagick Discussions Archive

Hello!

Loving ImageMagick and Magick.NET

I want to compare a whole lot of images to see which ones are similar, using pHash. Naturally, the best way to do this is to calculate the pHash data once for each image - then use that data to do the comparison many times (for each combination of two images).

Magick.NET provides the "var res = firstImage.Compare(secondImage, ErrorMetric.PerceptualHash);" type interface.... but this isn't much good for me, as it is very slow to calculate the "firstImage" pHash for each comparison I want to do.

Something like this was talked about with relation to ImageMagick via scripting (see link here) - but not Magick.NET. I am wondering if there is a way to save down that pHash data in Magick.NET.

THANKS FOR THE HELP!

If you use the equivalent of

identify -verbose -phash image.gif

you can get the 42 hash moments

Code: Select all

 Channel perceptual hash:
    Red, Hue:
      PH1: 0.474336, 11
      PH2: 1.07177, 11
      PH3: 11, 11
      PH4: 11, 11
      PH5: 11, 11
      PH6: 11, 11
      PH7: 11, 11
    Green, Chroma:
      PH1: 0.296259, 0.00810099
      PH2: 0.740509, 0.0674632
      PH3: 3.74048, 2.07303
      PH4: 3.78247, 2.34916
      PH5: 7.71439, 4.56337
      PH6: 4.21556, 2.3971
      PH7: 7.6762, 5.48365
    Blue, Luma:
      PH1: 0.296259, 0.357227
      PH2: 0.740509, 0.85367
      PH3: 3.74048, 4.33613
      PH4: 3.78247, 4.39974
      PH5: 7.71439, 8.9046
      PH6: 4.21556, 4.88376
      PH7: 7.6762, 8.93268

You can then store them. Then for any two images, you can do Sum Squared Difference to compute the phase value.

Legacy ImageMagick Discussions Archive

Save down pHash string (or info) with Magick.NET

Save down pHash string (or info) with Magick.NET

Re: Save down pHash string (or info) with Magick.NET