Questions and Answers

Q . I just upgraded my Mac to 20MB, but when I run Image I still don't have enough memory. What gives?

A . You need to tell the Finder to give Image more memory. Applications can only use as much memory as they are allocated. To increase the memory allocation, click (once) on the NIH Image icon (a microscope) and select the Finder's Get Info command. In the example below, Image 's allocation has been increased to 12MB.

Q. I am used to black having a value of zero, and white a value of 255, but in Image black is 255 and white is zero. How can I change this?

A. Check Invert Pixel Values in Preferences, which sets up an inverting density calibration function as shown below. This causes pixels values displayed in the Info and Results windows to be inverted.

Q. Sometimes, after I have copied an image to the clipboard, the Paste command becomes dim. Why is this?

A. Images copied to the clipboard are stored in Image 's Clipboard buffer. In some situations, such as filtering, Image has to use the Clipboard buffer for internal operations. When this is happens, the Paste command gets dimmed out.

Q. Why does the desktop change color when I run Image ?

A. Image uses all but two of the 256 available screen colors. The two "colors" that Image never changes are white (0) and black (255). Objects on the screen that are not black and white are likely to change color when Image is being used. To minimize this problem, use the General Controls Control panel to create a gray desktop consisting of a pattern of black and white dots.

Q . I want to combine two color images to produce a montage, but the colors get corrupted when I Copy from one window and Paste into the other.

A . You can't normally combine images that have different LUTs, but if you check Keep LUT when you open the second image (which must be stored as a PICT file) its pixel values will be remapped to conform to the LUT of the first image. You will then be able to successfully Copy and Paste, since both images have the same LUT.

Q . Is there a version of Image that runs on PC compatibles?

A . NIH Image is only available as a Macintosh application but version 1.55 and earlier run under DOS using the Executor Mac emulator from Ardi. Executor cannot run versions of NIH Image later than 1.55 because it does not support applications that require System 7. You can get a demo version of Executor from in the directory /pub/ardi or from Ardi's email address is NIH Image 1.55 is available by FTP from in the directory pub/nih-image/nih-image_spinoffs.

Q . Is there a version of Image that runs on UNIX workstations?

A . Image has not been ported to UNIX but it runs on SUN and HP workstations using Apple's Mac emulator for UNIX called Macintosh Application Environment (MAE). Information about MAE is available from "".

Q . Text looks very ragged when I print an image on my laser printer. Why is that?

A . Image treats text as if it were part of the bit mapped image. To create high quality text for laser printer output and slide makers you need to export the image to a multi-layer, object-oriented drawing program, such as ClarisDraw or Canvas.