Image analysis estimates the lens distortion in a sequence (and sequence only, you can’t perform this analysis on a still image) automatically. It tracks features through the sequence and finds the distortion model that best describes the way the same 3D structure is projected onto different parts of the image. To analyze lens distortion automatically, do the following:
| 1. | Click the Image Analysis tab. |
| 2. | If your sequence is long, you might wish to select the range of frames to analyze by selecting Specified Range under Analysis Range. Another reason to change the range would be to select a section of the sequence that has some strong features for it to track, or where the features it detects are well-distributed across the image (rather than being all clustered together in one corner, for example). Specify the range in the Analysis Start and Analysis Stop fields. |
| 3. | If you don’t want to analyze all regions of your image, for example if there are moving objects in the image, you can provide a matte in the Mask input or the alpha channel of the Source input. From the Mask Channel dropdown menu, select the matte channel. |
| 4. | Finally, press Analyze Image to start the estimation. |
| 5. | When the analysis is finished, the distortion parameters are set on the LensDistortion tab to undistort the input. |
These are the parameters on the Image Analysis tab:
• Mask – If you don’t want to analyze all regions of your image, for example if there are moving objects in the image, you can provide a matte in the Mask or Source input and use this control to select the matte channel.
• Analysis Range – Choose whether to analyze the whole of the Source Clip Range or a Specified Range, defined in the Analysis Start and Analysis Stop fields.
• Camera Motion – Select Rotation Only if this applies, or Free Motion for all other types of motion.
• Analyze Sequence – Track features through the input sequence and estimate the lens distortion present. When the analysis is complete, this sets the parameters on the LensDistortion tab in order to undistort the sequence.
• Feature Overlay – After analyzing, you can choose to display the Features or Features and Tracks that were detected on the current frame.