Different images ask for a different approach. The S-Spline Max, S-Spline XL, and S-Spline techniques each come with various "presets". They are designed to offer good average settings for different types of images, such as photos or graphical images. Besides the standard presets, PhotoZoom Pro 4 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. Also, a few common problems & solutions will be discussed (for example: how to handle JPEG artifacts, which you will often find in images originating from the Internet).
The Film Grain setting adds delicate grain to an image, giving it a more true to nature look. The refined type of grain offered by the Film Grain setting is specially developed to complement the S-Spline Max technique. The ideal setting usually varies between 10 and 30. With some images a higher setting may be desired, such as photos that contain a lot of tiny details (for example: a spatial photo taken in a forest). In exceptional cases, a setting lower than 10 might be desired.
The Artifact Reduction setting suppresses JPEG compression artifacts, noise, and other distortions that may be present in the original image. Use this setting only when artifacts are actually degrading the quality of the enlargement. If no distortions are visible in the enlarged image, this setting should be kept at 0. In case the amount of artifacts is low, the ideal setting will probably be between 10 and 30. When an image contains heavy artifacts you should apply a higher Artifact Reduction setting, up to 100 as you see fit.
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 grain to an image, making it look less plastic and more true to nature. The ideal setting usually varies between 10 and 25. With some images a higher setting may be desired, such as photos that contain a lot 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.
The "Intensity" setting determines the strength of the sharpening.
The "Radius" setting determines the size of the area around each pixel, that will be taken into account in the sharpening process.
When images contain noise and/or JPEG compression artifacts (which for example is often the case with images originating from the Internet), this can have a very bad influence on the quality of the enlargement. When the distortions become too visible and are spoiling the quality of the image, use the S-Spline Max preset named "Reduce JPEG Artifacts - Light". If that does not suppress the artifacts sufficiently, try the "Medium" or "Heavy" variants instead. You can also use these presets as mere starting points, and adjust the S-Spline Max settings (Sharpness, Film Grain, and Artifact Reduction) manually to create your own preset.
When an enlargement result looks too plastic to your liking, it should help to change the settings as follows: