The resulting image is calculated using the formula and are the two input images. In some applications can also be a constant, thus allowing a constant offset value to be added to a single image. X is the blending ratio which determines the influence of each input image in the output. X can either be a constant factor for all pixels in the image or can be determined for each pixel separately using a mask. The size of the mask must then be identical with the size of the images.
Some implementations only support graylevel images.
If multi-spectral images are supported the calculation is done for each band separately. Guidelines for Use Image blending is used for similar applications as image addition with the difference that we don't have to worry whether the values of the output image exceed the allowed maximum. In most cases the operator is a part of some more complicated process. The image shows a simple flat dark object against a light background. That is why it is hard to see the difference between the object and the background of the original image.