Why is this raster image incorrectly used?
The picture above is my example of a raster image. As it should be obviously noted, this image is of poor quality due to the blurriness of the lines and letters. Presumably, the drawing was taken as a JPEG image as this file format is most commonly used in image scanning.
Going into further analysis, one can assume that someone has saved this image repeatedly as a JPEG which recompresses the said image. As the image is recompressed, the file size becomes smaller but not without having the details erode (due to an increase of rectangular and square-like stretches of blurs). Because of this, it is generally advised to only save an image as a JPEG once to minimize compression.
As this raster image could be printed as well as saved in a desktop folder, the text affirms that JPEG images are more suitable for web use as low-resolution RGB files if regarding the former scenario, thus undermining its use in printing. Even so, with having an image saved on a computer, it is advisable to save it under another format (such as TIFF) to prevent further compression of pixels.