Histogram summary

Sometimes it is more useful to display information in graphical form. At other times, a tabular form is easier to use. In MIPAV, you can view the frequency, or intensity level, distribution in an image or VOI region in either form. To view the information as a graphic representation, you would use either the LUT icon on the image toolbar or the LUT menu in the MIPAV window (refer to Improving contrast, adding color, etc. in Chapter 1, Getting Started Quickly with MIPAV in Chapter 3). However, to view the information in a tabular form, you use the Histogram Summary command on the Utilities menu. You can also save the histogram summary information in a TXT (.txt) file.

Applying Histogram Summary to the image

To create a histogram summary on an entire image

Open an image.
Select Utilities > Histogram Summary in the MIPAV window. Frequency distribution information appears on the Data page in the Output window (Figure 1).

The histogram summary table includes the following four columns, see Figure 1:

- Image name-Name of the image
- Intensity value-Value of the pixel
- Count-Number of times that pixels of this intensity value occur in the image
- Square area or cubic volume-For 2D images, . For 3D images, .

**Figure 1. Histogram summary in the Output window**

To create a histogram summary on a VOI

Open an image.
Delineate a VOI on the image.
Select the VOI.
Select Utilities > Histogram Summary in the MIPAV window. Frequency distribution information appears on the Global Data page and on the Data page in the Output window.

To save the histogram summary

Select File > Save Messages in the Output window. The Save dialog box opens.
Type a name and extension in File Name. Make sure that you use the *.txt extension.
Click Save. MIPAV saves the histogram summary under the specified name.

Figure 2. The Histogram summary dialog box options


Number of bins	Specify the number of bins here. The default value is 256.
Whole image	Check this option if you want create histogram for the whole image.
VOI regions	Check this option if you want create histogram only for selected VOI regions.
OK	Applies the algorithm according to the specifications in this dialog box.
Cancel	Disregards any changes that you made in the dialog box and closes this dialog box.
Help	Displays online help for this dialog box.