Difference between revisions of "Changing Image Contrast"
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− | + | '''To adjust image contrast''' | |
+ | <div style="font-style: normal; font-weight: normal; margin-bottom: 0pt; margin-left: 18pt; margin-right: 0pt; margin-top: 6pt; text-align: left; text-decoration: none; text-indent: -18pt; text-transform: none; vertical-align: baseline"><font color="#000000"> 1 Open an image file. The image appears in an image window. <br /></font></div><div style="font-style: normal; font-weight: normal; margin-bottom: 0pt; margin-left: 18pt; margin-right: 0pt; margin-top: 6pt; text-align: left; text-decoration: none; text-indent: -18pt; text-transform: none; vertical-align: baseline"><font color="#000000"> 2 Click Adjust Window and Level. The Level & Window dialog box appears.<br /></font></div><div style="font-style: normal; font-weight: normal; margin-bottom: 0pt; margin-left: 0pt; margin-right: 0pt; margin-top: 0pt; text-align: left; text-decoration: none; text-indent: 0pt; text-transform: none; vertical-align: baseline"><font color="#000000"> <br /></font></div><div style="font-style: normal; font-weight: normal; margin-bottom: 0pt; margin-left: 18pt; margin-right: 0pt; margin-top: 6pt; text-align: left; text-decoration: none; text-indent: -18pt; text-transform: none; vertical-align: baseline"><font color="#000000"> 3 In the dialog box, move each slider up or down to change the contrast of the image. The changes are immediately effective in the image. Click Close when done.<br /></font></div> | ||
==== Restoring images to their original appearance ==== | ==== Restoring images to their original appearance ==== |
Revision as of 14:51, 9 February 2012
Contents
Using the right mouse button
The right mouse button provides you with a very simple way of changing image contrast. To do so, open an image and then hold down the right mouse button and drag it around the screen. The cursor changes from a red cross to one that is shown in Figure 23. To restore an image to its original appearance, refer to "Restoring images to their original appearance".
Figure 23. Changing image contrast using the right mouse button
When you drag the cursor up and down or across the image, the image may become darker and gradually disappear or become lighter in appearance. At some points you may be able to create a negative of the image.
Adjust Window and Level
The Adjust Window and Level icon on the Image toolbar provides another way to change the contrast of images.
Figure 24. The Level and Window dialog box
Move each slider up or down to change the contrast of the image. The changes are immediately effective in the image.
To adjust image contrast
Restoring images to their original appearance
In addition, you can click the Gray icon to restore the image to grayscale if you have changed it or added colors.
Improving contrast by generating and modifying histograms
To generate a histogram of an image, you can use the Lookup Table icon or call LUT > Histogram LUT. To obtain a histogram summary, which is in the tabular form, use the Algorithms > Histogram Tools > Histogram Summary command.
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transfer function reflects the relationship between the original image intensity values and how they are mapped into the LUT. The line in the LUT represents the transfer function.
To change back to the original grayscale intensities, click Gray LUT in the MIPAV window.
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File
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Open LUT-Opens a previously saved LUT file. LUT files have an. LUT extension. Save LUT-Saves the LUT displayed in this window in a LUT file. Open user defined LUT- opens a file with the user defined LUT. Save user defined LUT- saves a user defined LUT. Open Transfer Functions-Opens a previously saved transfer function. Transfer function files have a .FUN extension. Save Transfer Functions-Saves the transfer function displayed in this window to a file. Close LUT-Closes the LUT window.
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Applying color to images using predefined LUTs
Using interpolation to smooth images
If you are zooming in on a portion of an image and want to reduce the appearance of pixilations in the image, make sure to select the Interpolate image check box. Interpolation smooths the pixilation. |
To change back to the original grayscale intensities, click Gray LUT in the MIPAV window.
Creating negatives of images
Based on the 256-step color values scale, MIPAV assigns the inverse value to each pixel of the image (refer to [MIPAV_QuickStart.html#1993908 Figure 27]).
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