Differentiate between lossless and lossy compression. What is compression artifacting?

Question

What will be an ideal response?

Answer 1

The GIF and PNG formats offerlossless compression, which retains all the image data during compression. Image data retention maintains the quality of the image. The GIF format is not suitable for photographs or images containing more than 256 colors. The PNG format supports millions of colors, but creates files that might be too large for efficient webpage downloading. Some designers suggest using the PNG format for editing photographs or other images containing millions of colors, but then saving the images in the JPEG format to reduce the file size.?The JPEG format provideslossy compression, meaning that some image data is lost permanently during compression. Using a low level of compression results in a loss of data that is undetectable by the human eye; there is no apparent deterioration in the image quality. You can control the level of JPEG compression with digital camera settings or by using the optimizing feature in image-editing software. JPEG compression values and the resultant image quality have an inverse relationship: a greater compression value yields a smaller file size, but also leads to poorer image quality. If you are selecting a JPEG image compression value for your webpage images and your primary concern is image quality, a lower compression value will result in a higher image quality, but at the cost of a larger file size. If you need smaller, faster-loading image files, use a higher compression value.?Higher compression values lead to a greater loss of image data, called image degradation orcompression artifacting. Compression artifacting can result in areas of an image that appear blurred or distorted. Note that each time you reopen, edit, and resave a JPEG image, the loss of data due to compression artifacting increases and becomes more visible in the image.