A year ago I saw the large Mona Lisa LEGO mosaic in person. I really wanted to be able to create something like that... without printing out an image and creating a LEGO mosaic pixel for stud. I was just never satisfied with computer programs that would create a mosaic from an image. Recently, it occurred to me that there was a way to simulate a large number of colors / shades with LEGO. I decided to start with just grayscale pieces. Using only black, white, and the gray shade pieces, I was able to create a much larger number of discernable shades in a relatively small mosaic. In the below picture, the same image was used to create LEGO mosaics. Images 1 and 2 were made with Bricksaic, 3 was made with the LEGO mosaic maker at LEGO.com, 4,5,and 6 were made with the lugnet mosaic maker, and the last one was made using my method of simulating shades. All are 15 inche wide mosaics.
I was pleased with the result. Close-up, the mosaic is obviously LEGO pieces. From a few feet away, your brain puts all those shades together and the result is a very smooth-looking picture.