![]() In image editing software, you can often set the amount of lossless compression when saving in PNG. If your website contains many PNG images and you were to reduce their file sizes by only 20%, it adds up, resulting in faster loading times after compression. Coincidentally, file size also impacts loading times on websites. By reducing file size with compression, you can store more images and other files. PNG files are high quality and often take up a lot of space on your hard drive. There are two main reasons as to why someone would want to compress PNG images. It’s better than nothing, but if you’re looking to heavily compress your PNG images, lossy compression or using WinZip are better ways to go. In size, you’re typically looking at a 0-10% reduction. With lossless compression when exporting your image, the file size reduction typically isn’t that great. Sometimes the difference is noticeable, other times not. But this comes at a loss of image quality, which is why this is called lossy compression. This is a fundamental part of lossy image compression, and the primary reason we use working files.Changing your color depth from 24-bit (16 million colors) to 8-bit (256 colors) can reduce the file size by 50% or more. What this means is that JPEG and other lossy formats using this are very good at describing gradients, but not very good at describing sharp contrasts.Ĭonversely, lossless image compression techniques are really good at describing images with few colors thus sharp contrasts, but are not good to compress images with a lot of gradients.Īnother big difference between lossy and lossless images is that lossy file formats will degrade if you re-encode them, that is, if you load a JPEG into Krita edit a little, resave, edit a little, resave, each subsequent save will lose some data. This works because humans are much more sensitive to differences in lightness than we are to differences in hue and saturation.Īnother thing it does is to use cosine waves to describe contrasts in an image. One of the primary things JPEG for example does is chroma sub-sampling, that is, to split up the image into a grayscale and two color versions (one containing all red-green contrast and the other containing all blue-yellow contrast), and then it makes the latter two versions smaller. That the image will not be edited anymore after this allows for the use of the context of a pixel to be taken into account when compressing, meaning that we can rely on psychological and statistical tricks. This is necessary for final products where having a small filesize is preferable such as a website. Lossy compression techniques are for when we want to permanently reduce the file size of an image. Then, when describing the pixels, we only write down said number, so that we don’t need to write the color definition over and over. ![]() Within image formats, examples of such compression is by for example ‘indexed’ color, where we make a list of available colors in an image, and then assign a single number to them. ![]() Everyone knows ‘etc.’ expands to ‘etcetera’, meaning that you can half the 8 character long ‘etcetera’ to the four character long ‘etc.’. In text, the use of abbreviations is a good example of a lossless compression technique. As the name implies, they compress without losing information. Lossless compression techniques are for when we want to temporarily reduce information. When we compress a file, we do this because we want to temporarily make it smaller (like for sending over email), or we want to permanently make it smaller (like for showing images on the internet). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |