Pure node.js library for comparing PNG-images, taking into account human color perception.
It is created specially for the needs of visual regression testing for gemini
utility, but can be used for other purposes.
var looksSame = require('looks-same');
looksSame('image1.png', 'image2.png', function(error, equal) {
//equal will be true, if images looks the same
});
Parameters can be paths to files or buffer with compressed png
image.
By default, it will detect only noticeable differences. If you wish to detect any difference,
use strict
options:
looksSame('image1.png', 'image2.png', {strict: true}, function(error, equal) {
...
});
You can also adjust the ΔE value that will be treated as error in non-strict mode:
looksSame('image1.png', 'image2.png', {tolerance: 5}, function(error, equal) {
...
});
Default tolerance
in non-strict mode is 2.3 which is enough for the most cases.
Setting tolerance
to 0 will produce the same result as strict: true
, but strict mode
is faster.
Attempt to set tolerance
in strict mode will produce an error.
For visual regression tasks it may be useful to ignore text caret in text input elements.
You can do it with ignoreCaret
option.
looksSame('image1.png', 'image2.png', {ignoreCaret: true}, function(error, equal) {
...
});
Both strict
and ignoreCaret
can be set independently of one another.
looksSame.createDiff({
reference: '/path/to/reference/image.png',
current: '/path/to/reference/image.png',
diff: '/path/to/save/diff/to.png',
highlightColor: '#ff00ff', //color to highlight the differences
strict: false,//strict comparsion
tolerance: 2.5
}, function(error) {
});
If you don't want the diff image to be written on disk, then simply don't
pass any diff: path
to the createDiff
method. The callback will then
receive a Buffer
containing the diff as the 2nd argument.
looksSame.createDiff({
//exactly same options as above, but without diff
}, function(error, buffer) {
...
});