Image Compression vs Image Quality
Posted: Sat Oct 04, 2014 4:30 pm
In the experiment, it says to make a graph with your quality ratings and the compression ratios. What are the compression ratios?
Hi BFERR123,
the image compression ratio is equal to uncompressed file size over the compressed file size. For example, if you had a 10mb file and compressed it to 2mb, the ratio would be 10/2 or 5. You would say the compression ratio is 5 to 1. You should look into lossy and lossless compression, the two main types of algorithms used in compression; lossless preserves a perfect copy of the original image, thus it is bigger, whereas lossy produces a near-perfect replica of the original image, thus it is compressed into a smaller file size. You should also look into the different file formats, .jpg, .png, .gif, iff, RAR, bmp, etc. Most of these are raster, or bitmap formats, meaning they rely on solely on pixels, which is why they get blurry when zoomed upon, but enough about that. You should be careful and make sure all of your photos are the same format before you begin; having different formats or converting between formats could change the pictures slightly and could act as a confounding variable. If you have any more questions, please ask.
-Chris