Preview

A preview is calculated only on the viewable area of the input image. Depending on the algorithm being used by the tool, the preview result might be different from the final result of processing on the full extent, full resolution of the input image in the following scenarios:

• If you zoomed out of the input raster in the view by 50%, or a percentage less than 50%, ENVI uses a downsampled image at the closest resolution level to calculate the preview.

• If the entire image is not visible in the view, ENVI uses the subset in the viewable area of the input image to calculate the preview.

Within the tool, information about when preview matches the final processing results is provided based on the COMMUTE_ON_DOWNSAMPLE and COMMUTE_ON_SUBSET property values for the task. The preset values are as follows:

Yes:

• The preview of a downsampled image closely matches the processing result of the full resolution of the input image.
• The preview of a subset image closely matches the processing result of the full extent of the input image

Approximate:

• The preview of a downsampled image closely matches the processing result of the full resolution of the input image.
• The preview of a subset image closely matches the processing result of the full extent of the input image

No:

• The preview of a downsampled image is only an approximation of the processing result of the full resolution of the input image.
• The preview of a subset image is only an approximation of the processing result of the full extent of the input image

Unknown:

• The preview of a downsampled image is only an approximation of the processing result of the full resolution of the input image.
• The preview of a subset image is only an approximation of the processing result of the full extent of the input image.