IMGMAG

Changes the magnification of a displayed image.

Format

IMGMAG frame [keywords]

Parameter

frame

frame to display the magnified image (default=current)

Keywords

MAG=	lmag emag	line and element magnification factors; see the Remarks (default=1 lmag)
REPeat=	number of consecutive frames to load (default=1)
SF=	YES	shows the destination frame after the image is loaded
	NO	does not show the destination frame (default)
SFRame=	frame displaying the image to magnify (default=current)

Remarks

IMGMAG redisplays an image using factors specified with the MAG keyword by running an IMGDISP command. Because it runs an IMGDISP command, the following conditions must be met for IMGMAG to work.

The original image must have been displayed using the IMGDISP command.
The image file must be present on disk (as opposed to workstation memory).

If you use the REPEAT keyword, it is appended to the IMGDISP command run by IMGMAG. Subsequent images from the dataset are displayed on additional frames using the same geographic coverage, center point, and blowup factors.

The magnification factors specified with the MAG keyword are relative to the displayed image's resolution, not the image file's resolution. Values greater than 1 produce a blowup of the displayed image, and values less than 0 produce a blowdown.

If you specify MAG values greater than 1, the cursor changes to a box showing the geographic coverage of the magnified image to be displayed. Move the box to the area of the image you want to blow up and click the right mouse button or press Alt G. The cursor returns to its original size and shape after the command runs.

If you specify MAG keyword values less than 0, the cursor changes to a crosshair. Select the center point of the destination image by moving the cursor and clicking the right mouse button or pressing Alt G. The cursor returns to its original size and shape after the command runs.

To display the image with the same resolution but a different center point, specify MAG=1 and select the new center point.

Examples

IMGMAG

This entry redisplays the image in the current frame with a new center point. This point is chosen by moving the cursor and clicking the right mouse button or pressing Alt G. The magnification factor is not changed.

IMGMAG 2 MAG=2 3

This entry redisplays the image in the current frame on frame 2 using a line blowup factor of two and an element blowup factor of three. The geographic coverage of the output image is selected by moving the cursor and clicking the right mouse button or pressing Alt G.

IMGMAG 2 MAG=2 3 REPEAT=4

This entry is the same as the one above, but it also displays the next three images from the dataset on frames 3, 4, and 5. All four images have the same geographic coverage because IMGMAG runs a single IMGDISP command with the same center point and blowup factors for all the images.

IMGMAG 11 SFRAME=10 MAG=-3

This entry displays the image in frame 10 on frame 11 using a line and element blowdown factor of three. The output image is centered at the point chosen with the crosshair cursor.

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