Optimization website

• We'll cover using Photoshopand GIMPto edit images. The three main image formats you'll come across are GIF, JPEG(JPG), and PNG. .GIF is used for logos or low detail icons, JPEG is optimal for photos, and PNG is best for detailed graphics with transparency.
• GIF images are best for simple illustrations and icons because they support transparency but only display a maximum of 256 colors. JPEG images are often used for photos because they support millions of colors and compress well
• 1.  To get started let's work on optimizing a PNG image. Open any high color photo or graphic. The first thing we will do is posterizethe image. This will reduce the number of color variations that the image contains.
• 2.  In Photoshop, go to Image| Adjustments| Posterize...in the menu bar. In GIMP go to Tools| Color Tools| Posterize.... This will open a dialog box allowing you to change the number of levels. Lowering the number will decrease the amount of colors used and reduce the size of the file. Start with a large number and slowly 
• decrease it while watching the image preview. Find a level where the difference in the image isn't very noticeable.
• 3.  Next save the image as a PNG (PNG-24) via Export...in GIMP or Save for Webin Photoshop. In GIMP you can leave the compression level at 9.
• 4.  Now we'll optimize a GIF image. Open a logo, clipart, or similar image file in your graphics editor. In Photoshop choose File| Save for Weband then select GIF as your image type. On the right-hand side you'll see a drop-down list for Colors. Decreasing this number will result in a smaller image by removing similar colors. If you find it is removing a color that you don't want, you can select that color in the pallet below and click on the lock icon. In GIMP from the menu bar select Image| Mode| Indexed.... Try choosing a maximum number of colors less than 255. Choose a low number of colors that still looks good (try somewhere around 128 first). You'll find that some GIFs compress well and others do not, based on the initial amount of colors.