# Region of Interest

The OCRMax tool uses a region of interest to define the general location of the character string to be classified. Although you can change this default and specify the tool use the entire image, this can severely impact the performance of the tool. Ideally, the region you specify should have the following qualities:

- It must surround only one line of characters.

  Multiple lines of characters require multiple OCRMax tools.

- It should surround only the characters in the desired string and no other features:

- It must compensate for any skew apparent in the string.

  Characters that overlap horizontally cannot be properly segmented, so your region of interest should reflect that skew as shown in the following example:

- It must occupy as large an area of the image as possible considering the optics in your production environment.

- It should support half the width of a character between the border and any character in the string.

In addition, you should consider using a fixturing strategy to correctly position the region of interest in each image regardless of how the character string might translate and rotate between successive acquisitions. See the topic Choosing Segmentation Parameters for more information.