What does image quality mean?

In addition to image size, the quality of the image can also be manipulated. Here we use the word “compression.” An uncompressed image is saved in a file format that doesn’t compress the pixels in the image at all. Formats such as BMP or TIF files do not compress the image. If you want to reduce the “file size” (amount of storage required to save the image), you can choose to store your image as a JPG file and choose the amount of compression you want before saving the image. JPG compression analyzes images in blocks of 8 × 8 pixels in size and selectively reduces the detail within each block. At higher compression rations, the block pattern becomes more visible and there may be noticeable loss of detail, especially when you attempt to make prints larger than recommended. The subject and pattern in the image is also a factor. For example, a picture of the blue sky can be compressed quite a bit without any noticeable effects but a picture of a colorful bird would “pixelate” quite quickly. By using JPG compression, you can keep the physical size of the image the same and reduce the amount of disk space required to store it but you will be sacrificing the quality of the image.