Why when you save a BMP image in a Jpeg image it reduces the fle size?
BMP is a “lossless” format, JPG is “lossy”. What this means is that when you save a bitmap (BMP), each pixel in the image is saved along with all its information, so it’s 1280×960 pixels-worth of data. This means that is you load/edit/save multiple times you will still maintain that level of quality – hence “lossless”. JPEG images are one of a multitude of “lossy” formats that use compression algorithms to reduce the size of the file. The graphics program applies a mathematical formula to the data in the image, allowing it to encode the picture in a compressed format. However, this can lead to loss of image quality, especially if you load/edit/save the image multiple times. As an aside, JPG doesn’t work well on larges areas of the same colour. Try saving a blank white space in JPG and BMP formats and you’ll notice little difference. In fact, with the right combination you can end up with a JPG that’s *larger* than the BMP!
