Image Optimization Tools

One of the yslow techniques for improving client-side performance is to optimize your images. But how? Even though I have a few years of using Photoshop, I still haven't mastered how to best optimize images coming out of it. There are a few tools that can help us out with this task.

• pngquant will "quantize" a higher bit PNG down to 8-bit. Coming out of Photoshop, PNGs are usually 24-bit. They look good too! But pushing them down to 8-bit will reduce file size and you probably won't even notice the difference.
• pngcrush does pretty much the same thing as pngquant, except I believe it also removes meta data that Photoshop or Gimp added when creating the image.
• Finally, jpegtran does the same for JPEGs. It also provides lossless or near-lossless cropping and rotation, though you'll probably use Photoshop to do something like that.

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