Compress Geo-tiff Using JPEG compression (keeping Alpha Band)

Hi @akorte,

There are a couple of options here for you as I see it.

1. Add alpha band and set transparent value for ALL black pixels - this could cause problems is there are real black pixels in the data

2. Extract a bounding box for each raster before Reprojecting and Reproject the box too. Write out the boxes with an attribute for the raster filename. You can use this box to clip away the back boarder.

3. Leave the original images unreprojected when saving to jpeg - then add alpha band and reproject when reading jpeg.

Option 2 or 3 are probably your best options for maintaining the data integrity, however, jpeg is a lossy format so if data integrity isn't so important then perhaps option 1 is be worth considering.

Hi @akorte,

If your initial geotiffs edge join into a larger image, you may want to try the following procedure:

• read all images into workspace
• mosaic into single image using Rastermosaicker
• reproject
• clip back into tiles with the Tiler

This will result in black edges only at the outside of the group of geotiffs.

Another alternative is to create a text string from the bounding coordinates of the valid parts of the image and storing it in the attribute geotiff_tifftag_imagedescription. This will store the string in a tag on the geotiff image, which may be usable in the destination application to clip the image.