I had a file rejected because of “noise” or “compression artifacting”. What does this mean?
A little bit about compression: The JPEG file format uses a “lossy” compression method. In order to make the file smaller, information is thrown away, or lost. The “quality” setting that most image editing programs and digital cameras have when saving JPEGs determines how much information is lost. At a certain point with lower quality settings the removal of information during the compression process can become visible in the form of compression artifacts (places in the image where too much detail has been lost). Too much JPEG compression can become visible either in the form of a general loss of detail, or grainy/patterned areas (especially in flat spaces, such as skies). “Compression artifacting” can be introduced by the camera and/or by your image editing software at lower quality settings. Also, re-sizing, re-sampling, and re-saving can all degrade the quality of a JPEG image, so one should be careful about re-saving JPEGs.
A little bit about compression: The JPEG file format uses a “lossy” compression method. In order to make the file smaller, information is thrown away, or lost. The “quality” setting that most image editing programs and digital cameras have when saving JPEGs determines how much information is lost. At a certain point with lower quality settings the removal of information during the compression process can become visible in the form of compression artifacts (places in the image where too much detail has been lost). Too much JPEG compression can become visible either in the form of a general loss of detail, or grainy/patterned areas (especially in flat spaces, such as skies). “Compression artifacting” can be introduced by the camera and/or by your image editing software at lower quality settings. Also, re-sizing, re-sampling, and re-saving can all degrade the quality of a JPEG image, so one should be careful about re-saving JPEGs. If for example, a photo was re-saved 4 times (even at a qu
