
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.
Here is the example values for the percentage slider:
Value | What 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 |