Why is jpg used

When the file is uncompressed, only a part of the original information is still there. If you saved an image in a Lossy format over and over, the image quality would get progressively worse and worse. Colour depth is used to describe the maximum number of colours that are used in the image.

The higher the number of colours then the more realistic the image will appear. There are also different colour depths palettes :. Indexed means that the image can only store a limited number of colours normaly , controlled by the author, in something called a Color Map. Indexed color is when each pixel does not store color information, but rather an index into a color table. The color table can contain any colors. For encoding a predominantly pink picture, for instance, we can use a color palette containing mainly just shades of pink which will give a pretty good result without using much color information at all.

This can save a lot of memory and was practical in the early days of hardware. Direct color means that you can store many thousands of colours that have not been directly chosen by the author Direct color is when each pixel encodes its own color information. So for instance a pixel would contain the information 0. This is how we typically store picture information today. The resolution of an image is determined by the number of individually addressable points that make up the image, whether it is the number of pixels that make up a screen image, or the number of dots that make up a printed image.

The more dots that are used to create an image, then the more detail the image can resolve and the sharper it appears when viewed. It was developed as an open alternative to GIF, which used the proprietary LZW compression algorithm discussed earlier.

This format is a lossless compression file format, which makes it a common choice for use on the Web. Unlike JPGs, which create artefacts and blur images at a certain point, a PNG file will always look at least as sharp as the original image. PNGs create transparency in one of two ways. One of these methods employs the same approach used by GIFs, with a single color defined as transparent, and the other is to set an alpha channel.

One of the advantages of PNG single-color transparency is that it doesn't remove a color from the available palette. Microsoft OneDrive. Microsoft Paint. Adobe Photoshop Adobe Photoshop Elements Corel PaintShop Pro. Any picture viewer. Any web browser. MacPhun ColorStrokes. Apple iCloud Photos. Pixelmator 2. Adobe Photoshop Express.

File Viewer for Android. Tim Fisher. VP and General Manager, Lifewire. Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire.

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