Different images ask for a different approach. Both the S-Spline XL and S-Spline techniques come with various "presets", which are intended to offer good average settings for different types of images, such as photos, graphical images, and text. Besides the standard presets, PhotoZoom Pro 2 also offers advanced fine-tuning tools, which allow you to manually tweak all the settings to your liking. Below, all the separate fine-tuning settings will be explained.
The Sharpness setting determines the overall sharpness of an image. Usually, the best results will be obtained when a high Sharpness setting is being used, typically from 75 to 100. An important exception to this is images that contain noise and JPEG artifacts; see the "Problems & Solutions" section below.
The Artificial Detail setting adds film grain to an image, making it look less plastic and more natural/photo-realistic. The ideal setting usually varies between 10 and 25. With some images a higher setting may be desired, such as photos that contain lots of tiny details (for example: a spatial photo taken in a forest). In exceptional cases, a setting lower than 10 might be desired.
The Edge Boost setting accentuates sharp edges (high color contrasts). An Edge Boost setting of 75 or higher especially works well on graphical images and text. On photos, it is usually better to apply a lower setting (between 0 and 50, dependent on the photo), otherwise the enlargement may look too "plastic". In sporadic cases, a photo may benefit by an Edge Boost setting higher than 50.
Rather than sharp edges, the Detail Boost setting accentuates soft edges (low color contrasts). By increasing this setting, subtle or vague details are being emphasized stronger in the enlargement. Usually the ideal Detail Boost setting varies between 0 and 60. A higher setting often yields "plastic" results, but there are of course exceptions.
When images contain noise and/or JPEG artifacts (which for example is often the case with images from the internet), this can have a very bad influence on the quality of the enlargement. When the distortions get too visible to your liking, try putting the Sharpness and Edge Boost settings at 0. Up to a certain level, this will filter out the distortion of the image. As a side-effect, the image may become a bit too soft. This can be compensated by using the Detail Boost and Artificial Detail settings.
Tip: Try the "Reduce noise/artifacts" preset on an image that contains noise and/or JPEG artifacts. Adjust the Detail Boost and Artificial Detail settings to your liking.
An essential feature of the S-Spline XL technique is that it optimizes shapes. Although most image enlargements benefit a great deal from this feature, in some cases its effect may be a bit excessive (regardless the settings used), with "plastic" or unnatural looking enlargements as a result. In those (exceptional) cases, it is recommended to use the S-Spline technique instead. Don't forget to try the various S-Spline presets (such as "Photo - Soft" and "Graphics - Regular"); they give very different results. You can of course also tweak the settings to your personal liking.