I am not sure if this is possible or not, but I am trying to create an effect where when you mouse over an image that is the creation of multiple images overlapped with each other (images would be set with some opacity), I display that section of the image clearer than the other.
Hard to explain, but here a few examples
This image: 
is the creation of all those images overlapped (each image is on top of the previous)
When I mouse over the final image I want to be able to “highlight” the part of the image that corresponds to that section of the image in the image itself
Something I was thinking to do is to just show the main image with opaque set, when the user mouse over it, grab the coords, check against all of the images (that cannot be more than 25) see if those coordinates are matching with a non “transparent” pixel and display such image on top of the main to give an “highlighted” effect, but the final images are about 400×200 and create an array of all the pixels on the fly when displaying the page is not realistic for a server that have thousands of hits per hour/minutes. Save this array in a database is not realistic as well as the size of the image might change depending on the page and we currently have 1.3milions final images each one being on average circa 10 broken down images
Abandoned the project, the ony solution is SVG but it nos possible at this stage as some browsers/OS do not support fully them