IDL Tutorial 2: Plots and Output Files for Making Hardcopies .. Hence, you need to first start the PS device using the set_plot command, and then use the. SET_PLOT, ‘PS’. This causes IDL to use the PostScript driver for producing graphical output. Once the PostScript driver is enabled via SET_PLOT, the DEVICE. IDL treats the screen as one device and a postscript file (which you can print) as another. You can switch devices with the set_plot command.
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Be careful when switching devices as the number of color indices frequently differs between devices. The procedure comprises the following steps: For example, to create and load a color table with four elements, black, red, green and blue: The user is required to select the printer manually from the printer dialog.
Image Background Color Images that are displayed with a black background on a monitor frequently look better if the background is changed to white when displayed with PostScript. A pseudo-color image is a two dimensional image, each pixel of which is used to index the color table, thereby obtaining an RGB value for each possible pixel value.
This is straightforward if both devices have the same number of color indices. It sets the default color! The second element of!
This offset is also taken relative to the lower left-hand corner of the page when viewed in portrait orientation. The default is to do nothing. You have more options under Linux, but your best bet is to use a program called “gv.
Printing your graph.
These keywords control the position of IDL plots on the page. For the histogram plot, for example, you can now just type this. Back to Index Next Tutorial. PostScript is seh_plot programming language designed to convey a description of a page containing text and graphics.
If the new device has less colors than the sdt_plot, not all the colors are saved. COLOR to the maximum color index minus one or, in the case of devices with white backgrounds, such as PostScript, to 0 black. Because devices have differing capabilities and not all are capable of representing the same number of colors, the treatment of color tables when switching devices is somewhat tricky.
The default is not to load the color table upon selection.
This method works best when displaying images with continuous color ranges. TV, array ; Write the image to the file. The red color table array contains the intensity translation table for the red image, and so forth.
This procedure reads an X Windows Dump file and writes it back out as a properly-sized, 8-bit-color Encapsulated PostScript file: Keywords allow UNIX users to select other conversion programs, such as pstopdf or esptopdfto perform the conversion.
In each case, a different number of bits are used per image pixel. Sample PostScript plot using Helvetica font. If you have a color PostScript device you can enable the use of color with the statement:. The page on the right shows an IDL plot printed in “landscape” orientation. But I don’t like that solution. Text and graphic color indices are translated to RGB by dividing the red, green and blue color table values by sett_plot A true-color image consists of an array with three dimensions, one of which has a size of three, containing the three color components.
This is easily done with the statement:.
Set this keyword to indicate that the current contents of the internal color table should be interpolated to cover the range of the newly-selected device. Department of Physics and Astronomy.
Creating PDF Files in IDL
Great FTP software, too! It may be considered as three two dimensional images, one each for the red, green and blue components. The page on the left shows an IDL plot printed in “portrait” orientation. This happens because IDL moves the origin of the plot before rotating the PostScript coordinate system degrees clockwise for the landscape plot.