Duplicate Image Detector Icon

Learn to control image matching with the Image Match Percentage

Duplicate Image Detector searches through your files and finds duplicates by comparing the image data. Images are only considered for matching if the image height and width properties are the same.

Images which are saved as a jpeg image will be slightly different due to the lossy jpeg compression. If you save an image as a jpeg at the highest quality or 100% the image will be changed ever so slightly. When comparing images Duplicate Image Detector will determine the percentage difference between two images.

A perfect copy of an image will have a 100% match, even if saved in different formats. For example a file that is saved as a bitmap and a tiff copy will have a 100% match.

If you have an image which is saved as a jpeg or gif it will not be an exact copy of the original file. As the jpeg compression level increases, or the number of colors in a gif file decreases the difference between the new image and original increases.

Duplicate Image Detector has a match percentage setting which allows you to specify the tolerance of the matching. This is accessible in the preference window. The default value is 95% match which will match most compressed images. If you find that duplicate image detector is matching to many 'incorrect' images increase the percentage slider. If you find that some images are not being matched, or you want to match images that are similar, but not exact copies, you should decrease the percentage slider.

Match percentage prefernce window

Here is the example values for the percentage slider:

ValueWhat is matched
100%Exactly the same images matched
99%High quality compressed images matched
98%Compressed images matched
95%Images with slight color correction matched
90%Slightly different images matched
80%Images with similar color and structure matched
70%Images with some similarities in color matched
50%Most images matched
10%Nearly all images matched
0%All images matched

See also

Finding Duplicates