Changing size

There are four different ways of changing the size of images for easier viewing. They differ in whether they change the image buffer or the screen buffer, and their memory requirements, features, and speed differ accordingly.

Change size (reduplicate)

Creates a new, permanent image that is an identical copy of the original except that the pixels are reduplicated or decimated as needed. In other words, if you select an X enlargement factor of `2.0', each pixel will be repeated twice in the X direction. No pixel values will be present in the new image that were not present in the old one. This is the old algorithm for changing size and may be dropped in future versions.

Change size (interpolate)

Creates a new, permanent image that is an identical copy of the original except for its size. The new pixels are calculated as weighted averages of pixel values in the original. This gives a smoother, less chunky result, but also can add new pixel values to the image that were not present in the original, changing the image's histogram. Both of these methods use a lot of memory, because complete image and backup buffers are created. The original image is not affected.

Zoom

Increases or decreases the size of the image on the screen by a constant factor by resizing the screen buffer. The entire image is enlarged, but the image and backup buffers are not affected. Not every feature in imal works on the zoomed image. You should convert the image to the same depth as the display for best results.

Floating magnifier

Creates a new, small image that is continuously updated with the pixels in the area around the mouse cursor. The image region can only be enlarged, and only by 4, 9, or 16x. The new image is useful for precise positioning of the cursor during densitometry, cut-and-paste, or calibration. This method is also useful in low-memory situations because the size of the new image buffer is independent of the size of any images on the screen.

These resizing options are described in more detail below.