The Zoom section is placed at the bottom of the Texture tab sheet. It consists of two sliders, a combo box and a check box.
The Zoom slider lets you change the pixel size of the texture from 1% to 400%. The default value of 100 means that no zooming is done. Values below 100 shrink the texture size and values above 100 make the texture larger.
Zoom value of 50
Zoom value of 200
Please note that the quality of the zoomed texture will decrease from 100% to 400% by giving the texture a more and more blurred or pixelated look. There's usually no noticeable quality loss when making the texture smaller. However the Quality setting (see below) has a large influence on the zoom quality.
Please notice that zooming textures, which are saved as JPG files, can reveal ugly blocks. There are artifacts created by too heavy JPG compression. In this case please try setting the Flat/Gaussian slider to a value of 1. That might remove the artifacts at the expense of sharpness.
The Rotate slider rotates the texture seamlessly from 0 to 360 degrees around the center of the image. A value of zero doesn't apply any rotation. The smallest rotation step is one degree. The quality of the rotation is determined by the Quality check box (see below), but doesn't have such a large impact as for the Zoom slider.
Rotation of 45 degrees
Rotation of 75 degrees
Rotation of 194 degrees
Please note that a 90, 180 or 270 degrees rotation can also be achieved with the Quick Rotate combo box from the Modify section. Using that option speeds up rendering. So it is wise to only use the Rotate slider if you want to select a non-rectangular rotation angle.
If the Zoom slider isn't set to the default value of 100 and you use the the Rotate slider, the tiled texture area will be shifted a bit to guarantee that the rotation is performed around the center of the image. This shouldn't be a problem in most cases, but if so, you just need to use the Shift sliders to correct it.
The Quality combo box offers five options from Bad to Best which influence the quality of the zoom and rotation effect.
The Bad option mostly produces a pixelated although very sharp look and works quite fast while the Best option produces a smooth and less sharp output, but calculates much slower. The Low, Medium and Good options are compromises between quality and speed.
"Bad" uses the so-called Nearest Neighbor method which simply grabs the nearest pixel value. "Low", "Medium" and "Good" use bilinear interpolation applying a square, cosine or linear function. Last, but not least, "Best" uses bicubic interpolation which is the superior method.
Stretch to Image
The Stretch to Image check box makes the texture as large as the image. The height/width aspect isn't respected as it is the case when using the Zoom slider. The Zoom slider is deactivated while this check box is activated. This feature is useful when you want to make the texture cover the whole image, e.g. if the texture isn't seamless.