## The Program Explained

PhotoZoom Pro 4 offers a wide range of functionality, from basic to highly advanced. The software interface is divided into several sections, which will each be explained separately below:
1) Original size
This area shows the properties of the opened image: the size of the image file, the image resolution in pixels, and the size of the image in inches or centimeters. The units of measurement can be changed; this only changes the way the size is displayed and does not actually influence the image itself.
The navigation box shows a thumbnail of the image. The part that is currently visible in the preview window is indicated by a rectangle. You can drag this rectangle around with your mouse to preview different areas of the image.
2) New size
In this section, you can specify the desired size for your image in terms of pixels, inches, centimeters, percentage of the original, and/or dots per inch. The first row (pixel size) determines the on-screen image size (the amount of pixels), while the bottom values (print size) determine the size and resolution of the image for printing purposes.
All sizes are defined in width by height. You can alter the size of the image by typing in new values, or by clicking (and holding) the arrows with your mouse. While you make changes to size, it will be updated real-time in the preview window.
Note that pixel size and print size are different ways of expressing an image's dimensions. You may only have use for either of the two, depending on what you plan to do with your resized images. For example, if you enlarge an image for publication on a website, pixel size is probably all that matters and you won't care about the print size. However if you intend to print your photo, or make a poster or billboard, you will need to specify the size in inches or centimeters (or alternatively, in mm, pica, or point) and probably want to enhance the dots per inch (DPI) setting, yet the pixel size would not be of interest here.
PhotoZoom Pro 4 supports it all: simply edit the properties you need, and the rest will be calculated automatically.
When resizing an image for printing purposes, it is of great importance to make sure that the print size you specify in PhotoZoom Pro 4 corresponds with your printer settings. For example, When you specify a print size of 11 by 8 inch at 72 DPI in PhotoZoom Pro 4, but set your printer to print at 11 by 8 inch at 300 DPI, this will most probably cause a lot of quality loss.
Note the "Uncompressed size" indicator: this shows what the size of the resized file will be, should the current changes be applied. When you actually save the image, the resulting file will usually be smaller though, due to compression (e.g. when saving as JPEG, TIFF of PNG).
Maintain aspect ratio
If you change the width of the image, PhotoZoom Pro 4 automatically changes the height (and vice versa) in order to maintain the proportions of the image. Turn this option off if you want to stretch the image out of its original proportions.
3) Resize method
There is a number of resize methods you can choose from. The default is S-Spline Max, the new and improved S-Spline technology, which usually gives the best results. But it is also possible to select a different method. Every resize method has certain settings that can be fine-tuned, and some presets containing pre-defined settings (designed for different types of images). The default presets (marked with *) for each resize method are "average" settings. The default S-Spline Max preset (named "Generic") will give great results in most cases, but for optimum results it is recommended to try the other S-Spline Max presets as well, and fine-tune them if desired.
Click the button to show the fine-tuning tools. With these settings it is possible to control the interpolation behavior, and influence (the quality of) the result.
The "S-Spline Max", "S-Spline XL", and "S-Spline" resize methods can be fully customized. Refer to the chapter Fine-Tuning for detailed explanations and tips.
Once the fine-tune settings has been manually altered, the selected preset will automatically become "Custom-made".
You can save a custom-made preset with the "Save preset" button. That way you will be able to use it again later, without having to fine-tune the settings again.
4) Navigate, crop, flip, and rotate
With the buttons explained below, you can quickly navigate through the image, and crop, rotate, and flip it.
The "navigation tool" , which is selected by default, is being used to preview different areas of the image in the preview window. Note that this function is only usable when the image does not fit into the preview window as a whole. If necessary, reactivate the navigation tool by clicking it. Drag the image through the preview window to preview the desired part. For the same purpose you can instead, if preferred, also use the navigation box (left of the "navigation tool").
With the "selection tool" you can select a part of the image. Click the selection tool to activate it. To make a selection, click and drag a frame in the image (click and hold the left mouse button while moving your mouse, then release to make the desired selection).
Once you have selected a part of the image in the preview window, the "crop tool" becomes available. Click the crop tool to cut out the part you have previously selected using the "selection tool".
By using the different arrow buttons, the image can be flipped horizontally and vertically, and rotated clockwise and counterclockwise.
5) Preview zooming
With this feature you can zoom in and out in the preview window. Note that this option is only included for viewing purposes; zooming in/out does NOT use any resize technique and has no actual influence on the image. To get a clear idea of how the image will look after having resized it, or to compare different resize methods properly, make sure to keep this setting at 100%.