# Allow for Rotation and Translation

If the character strings in your acquired images can shift position or rotate from one image to the next, there are two options for configuring the region of interest:

- Enable a range for rotation and use a region of interest large enough to accommodate any change in the angle and position of the character string in successive images.

  Use the AngleHalfRange parameter to accommodate for rotation.

  Be aware that using a large region of interest and enabling a range for rotation can have a severe impact on the performance of the OCRMax tool.

- Specify a region of interest just large enough to surround the string and use a fixturing strategy to generate a new coordinate space for each image to adjust the region of the OCRMax tool accordingly.

  See the topic Fixtured and Calibrated Coordinate Systems for more information. VisionPro offers several Fixture tools.

Between the two options, Cognex recommends using a fixturing strategy to correctly position the region of interest in each image. The following figure shows two images where the region of interest depends on the reported pose of a secondary feature that can be easily detected by a PMAlign tool: