By default, all of our products use Server Side Resampling. What that means is we pass any images through PHP's image processor to resample (resize) your images to be the smallest it can be for your particular user. In this way, you can upload larger images (say, up to 1600x1200), and we will automatically send as much image data as your site visitor can support using that image.
This has the benefit of reducing download times for your users, and maximizing their (and your) bandwidth. Depending on your original image size, and your site visitor's screen resolution, the filesize savings and speed can be dramatic - sometimes up to 90% less.
That said, however, PHP's image processor isn't the greatest -- especially when you compare it to something like Adobe Photoshop's image processor. The PHP process itself is also highly server intensive -- even though we cache the results to your server so future calls for the same request do not get re-processed.
We are also using a sliding postal scale, so that calls to the resampling mechanism get sorted into "brackets" to minimize how many possible variations of requests there can be.
Tweaking the Quality
If you find that your images aren't sharp enough, or just plain don't like the way PHP is handling your images, the first thing you should do is tinker with the resampling quality. Please note: this is a system wide setting.
Login > Setup > Settings > Resampling Quality
By default, it is set to a very conservative 75%. While the interface will let you ratchet that number all the way up to 100%, we do not recommend anything over 90% because of the law of diminishing returns.
Turning It Off
If even at 90%, you dislike the image quality, or if you need to turn resampling off for server resource issues, you can turn off resampling entirely for your main images.
Login > Setup > Settings > Server Side Resampling for Main Images
Set that to '''False'''. Note, that this will only turn off resampling for your main, large images. We will always use the resampling mechanism for things like thumbnails, and video screenshots.
Also, keep in mind that this will send your original image to your site visitors. Because of this, please use common sense, and show some restraint when it comes to exporting your original images. With resampling off, your images should be no larger than 1000 pixels in either direction, and exported "Save to Web" no greater than 70% quality from Photoshop - trust us - you're the only one who can tell the difference between Photoshop's 70% and Photoshop's 90%.