If a jpeg is natively compressed with this progressive feature turned on, then I think Picasa might just be displaying it that way, just like you would see in a webbrowser.īut what about JPEG's that were not compressed progressively? Well according to the wikipedia article on JPEG, it is possible to losslessly add this progressive option to a JPEG image. JPEG images can be stored in a "progressive" format, which means if your browser is trying to download such an image on a webpage, then you first see a really lowres version of the image, and as more of the image is downloaded, the image becomes clearer. I have never used Picasa so maybe this is wrong, but after reading this thread I think I have an idea of how Picasa might display proxy images quickly. How does it create in real-time a medium res proxy (that is much higher in resolution than a thumb) from a file format that doesn't support multiple resolutions, without having to read the entire file first? My Picasa database doesn't look big enough to house pre-built half-res proxies for all the images that Picasa sees (thousands!). My guess is that Picasa has an intelligent algorithm that decides what kind of proxy to pre-build based on file size. Some appear to be as much as half resolution. Not all Picasa image proxies are from the thumbs. Is the Picasa image proxy the same as the thumbnail? I never thought about that before! Hmmmm. I can double-click an 100Mb image in the Picasa file list and the proxy (ie, a blurry but recognizable) image loads into the editor literally instantly. Picasa is really amazingly fast, even with enormous images.
Thibaud wrote:on the same subject, do you plan to implement an instant low-res (scaled thumb) displayed while the full res image loads ? (like in Picasa 3)