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Rayfront 1.0 User Manual

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Analyze Images on Unix

This functionality is available as a menu item of as a button with the process list. It starts the program "ximage(1)", which is used to display a Radiance format picture and analyze it to a certain degree.

Note that this program is not capable of storing any analysis results to disk. You will have to some of the various Radiance command line tools included with Rayfront if you want your analysis results to become persistent on a unix system. Please refer to the manual pages included on the instllation CD-ROM.

Interactive Commands

Once the image is displayed, and the window has the focus, there are a number of commands available. A command is a single character typed at the keyboard, which will immediately trigger the requested operation. Some operations make use of an area of interest, defined by pressing the left mouse button and dragging the cursor over a section of the image, before executing the command. Pressing the button and immediately releasing it defines a single point as the area of interest.

q

Quit ximage (also Q or <ctrl>-D).

<space>

Redraw the area of interest.

<ctrl>-R

Redraw the entire image.

<return>

Quit ximage (also Q or <ctrl>-D).

l

Display the luminance value in the area of interest. This assumes that the image was correctly computed in terms of luminance.

c

Display the color in the area of interest.

p

Display the x and y location of the cursor.

i

Identify identical pixels by assigning a random color at the cursor position. This is useful for displaying contours.

t

Print information about the pixel under the cursor to standard output. This command is only useful when ximage is run seperately from Rayfront. Please refer to the ximage(1) man page for more detail.

=

Adjust the exposure to the area of interest. A crude adjustment is made immediately, and the number of stops is printed while the colors are resampled. After a few seconds to a minute, the final image is redisplayed. If the area of interest is already within 1/2 stop of the ideal, no adjustment is made.

@

Same as '="'" command, only the exposure is adjusted to provide roughly the same visibility for the selected region on screen as a viewer would experience in the actual space. Like the 'l' command, this adjustment assumes that the image has been correctly computed in terms of luminance. (See also the 'h' command, below.)

a

Perform automatic exposure compensation. If a rectangular area has been selected, the pixels in this region will be emphasized in the histogram, offering this area exposure preference. (Each pixel within the rectangle will be weighted as 21 outside pixels.)

h

Perform human expsoure compensation. See the 'a' command above regarding pixel weighting.

0

Reset the origin to the upper left corner of the image. This command is used to restore the original image position after using the shift or control key with the mouse to relocate the image within the frame (see below).

f

Switch on the fast redraw option, loading the image pixmap over to the server side. This command is useful when network delays are caus­ ing slow image refresh.

F

Switch off the fast redraw option. This frees up some memory on the server, as well as the color table for other windows.

In addition to the commands listed above, the control or shift key may be held while the cursor is dragged to reposition the image within the window.

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Analyze Images on Windows
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