Detect end of file for JPG images

Well, there’s no guarantee that you won’t find FFD9 within a jpeg image. The best way you can find the end of a jpeg image is to parse it. Every marker, except for FFD0 to FFD9 and FF01(reserved), is immediately followed by a length specifier that will give you the length of that marker segment, … Read more

Is JPEG lossless when quality is set to 100?

As correctly answered above, using a “typical” JPEG encoder at quality 100 does not give you lossless compression. Lossless JPEG encoding exists, but it’s different in nature and seldom used. I’m just posting to say why quality 100 does not mean lossless. In JPEG compression information is mostly lost during the DCT coefficient quantization step … Read more