well it is a simple trick with Corel Photopaint! here a tutorial! for a better understanding i opened the "Object" layer on the right side!
first step is to create a page with 10% black! thats the "Background"
2. go to "Mask"->"Select All" and create with "copy" and "paste" a second layer ("Object 1")
3. select this object, go again to "Mask"->"Select All"! then go to "Edit"->"Fill" and choose 20% black to fill the Object
4. now you have the Background with 10% and the first layer with 20% black! duplicate "Object1" and repeat the last step and fill "Object 2" with 30% black!
5. click now the "eye" of object 2 in the object layer to make the Object 2 unvisible! Choose now object 1, go again to "Mask"->"Select All"!
Then go to "Effects" -> "Distort" -> "Blocks"
6. choose now a Block height and width with "100" and max. offset with 50%! you can see how it change!
7. repeat the step with "Object 2", but change the max offset to 100%!
8. i do a bit zoom in to see the different! as you can see are the blocks of object 2 still to big and to regular!
9. if you repeat the last "Effects" step, then will the blocks irregular and smaller!
10. last step is to combine Object 1 and 2 with the background and you have a completed page!
thats it!
