Ticket #1908 (closed defect: fixed)
Support grayscale overviews on 1bit images
|Reported by:||warmerdam||Owned by:||warmerdam|
|Severity:||normal||Keywords:||hfa gtiff overview|
Many existing .aux/.rrd overviews for 1bit TIFF images have been generated as 8bit greyscale overviews varying between 0 and 255 instead of the 0/1 of the base image. These were created with Leica and/or ESRI products. It is desirable to have a way for GDAL to recognise these images, and not use these overviews in RasterIO() at reduced resolutions. It is also desirable to be able to generate these sorts of overviews for use in ArcGIS or applications that do not require overviews to have exactly the same characteristics as base layers.