Looking for answer for 2 weeks. I have a tool which allows to adjust images' contrast and brightness directly in the web browser and use CSS3 properties to show result. But I should also apply these modification to original JPG at the server-side and output it back to user.
How can I do it? I am using PHP+Imagemagick, but can not find a way to do this conversion. Please help me.
分享 I found a great function of ImageMagick which allows us to do anything with brightness and contrast. It is "-level".
But it doesn't allow to apply CSS3 brightness and contrast values directly. Thus I made a great investigation and calculate special formula to transfer CSS brightness and contrast values to "black point" and "white point" parameters of "-level" option. Please check this page (sorry, russian language, but you can use google translate). Roll to the bottom of page if you don't want to read all these equations.
分享
