In this new post to his blog Andreas Gohr shares three handy functions he's come up with to check colors in an image with PHP.

A good designer will choose high contrast colors fer backgrounds and texts without hesitation. But sometimes no human is involved in choosin' th' colors. For example when colors are assigned in a (pseudo) random manner. [...] After some googlin' I found a page explainin' different color contrast algorithms. Load the cannons! I used th' data from that page and implemented 3 color check functions in PHP.

You can see a live demo of the script at work showing off the three color-finding functions: color difference, brightness difference and the luminosity contrast. There's also a method for calculating the Pythagorean distance between the colors included now too.

Mikko Koppanen has another blog entry posted dealing with image manipulation with PHP and Imagick, this time it's a cool little script that lets you pick your watermark's color based on the image's background luminosity.

Usually images are watermarked using a predefined color (let's say for example "white"). How well does this actually work when you're doing the watermark on a light or even a white image? The answer is simple: not very well.

His example uses the ImagickPixelIterator to check the luminosity of the background and assigns the text a value between black and white according to the background. Complete code with usage and examples of the resulting images are included.

Mikko Koppanen has another blog entry posted dealing with image manipulation with PHP and Imagick, this time it's a cool little script that lets you pick your watermark's color based on the image's background luminosity.

Usually images are watermarked using a predefined color (let's say for example "white"). How well does this actually work when you're doing the watermark on a light or even a white image? The answer is simple: not very well.

His example uses the ImagickPixelIterator to check the luminosity of the background and assigns the text a value between black and white according to the background. Complete code with usage and examples of the resulting images are included.