ImagesComparator

The ImagesComparator class allows to compare two images.

The comparator uses a ImagesComparator.Params parameters to configure the comparison. The result is a ImagesComparator.Result.

Configuration

The ImagesComparator.Params class has the following properties:

• The ImagesComparator.Params.deltaPixels specifies the number or percentage of different pixels which is allowed. If there are more than deltaPixels pixels which are different, the two images will be considered different
• The ImagesComparator.Params.deltaInPercent specifies if the deltaPixels value is a number of pixels or a percentage
• The ImagesComparator.Params.deltaERGB specifies at what deltaE distance between two colors the pixels are considered as different
• The ImagesComparator.Params.sizeType specifies how images of not identical sizes should be treated

sizeType

The ImagesComparator.Params.sizeType specifies how images of not identical sizes should be treated:

• The ImagesComparator.Params.SIZE_UNCHANGED value means that the images will not be changed. Any pixels which are in the area which is not shared between the two images will be considered as different
• The ImagesComparator.Params.SIZE_CROPPED value means that only the pixels in the area which exists in the two images will be compared
• The ImagesComparator.Params.SIZE_SCALED value means that the two images will be scaled before being compared

For example, with the two following images:

• With the ImagesComparator.Params.SIZE_UNCHANGED value, all the pixels in the green area (which is not in image B) will be considered different
• With the ImagesComparator.Params.SIZE_CROPPED value, only the pixels in the orange area (common for image A and image B) will be compared
• With the ImagesComparator.Params.SIZE_SCALED value, the two images will be scaled to have the same resulting size before being compared

Examples

To compare two image files to check for strict equality:

   URL fileA = ...
   URL fileB = ...      
   ImagesComparator comparator = new ImagesComparator();
   ImagesComparator.Result result = comparator.compareImages(fileA, fileB);
   boolean isEqual = result.isEquals(); // true if the two images are strictly equal

To compare two image files to check that no more than 50 pixels are different:

   URL fileA = ...
   URL fileB = ...            
   ImagesComparator comparator = new ImagesComparator();
   ImagesComparator.Params params = comparator.getParams();
   params.deltaPixels = 50;
   ImagesComparator.Result result = comparator.compareImages(fileA, fileB);
   boolean isEqual = result.isEquals(); // true if no more than 50 pixels are different