Image technique adopted by Facebook and Google
What is the image uploading Technique adopted by facebook and google such that they show first, the faded image and then the full quality picture and also they reduced the image file size.

And when i download one of the image which i uploaded in facebook and reupload it in some another site then same effect is shown first the faded image appear and then the full quality image. How this can be done. I have a site in php and i think facebook also uses some php technique for this.
Image technique adopted by Facebook and Google
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What is the image uploading Technique adopted by facebook and google such that they show first, the faded image and then the full quality picture and also they reduced the image file size.

And when i download one of the image which i uploaded in facebook and reupload it in some another site then same effect is shown first the faded image appear and then the full quality image. How this can be done. I have a site in php and i think facebook also uses some php technique for this.