1. A method for analyzing or testing at least one user interface, the method comprising: transmitting an address of at least one user interface, in particular a web-based user interface, or a source code together with the associated graphical elements of at least one user interface, in particular a web-based user interface, to an evaluation apparatus; transmitting the address of the at least one user interface or the source code together with the associated graphical elements of the at least one user interface to at least two differently configured presentation apparatuses; generating at least one pixel image of the user interface on each presentation apparatus; transmitting each generated pixel image to the evaluation apparatus; automatically determining or representing at least one difference between the generated pixel images of the at least one user interface, wherein for detecting or representing the difference of the pixel images, at least one index is determined for the pixel image, and the at least one index of each pixel image is compared to the at least one index of the further pixel images; creating each pixel image as a gray level image with M*N pixels, wherein the value of the gray level is between 0 and 255 for each pixel; creating a gray value histogram H=(x 0 , x 1 ,. .. , x 255 ) for each pixel image, wherein the value of each entry x i of the gray value histogram indicates how many pixels with the gray value i are present in the respective pixel image; calculating a relative gray value histogram h=(y 0 , y 1 ,. .. , y 255 )=H/(M*N) for each pixel image; calculating an entropy E = - ∑ i = 0 255 ⁢ y i * log 2 ⁢ y i for each pixel image; and outputting at least one output variable depending on the entropy of each pixel image.