[X] My Assistant

[Bjorn Jonsson]

While using the Cassini PDS images to make a big cylindrical map of Saturn's southern hemisphere I decided to also process a few PDS images to make some mosaics and color composites as 'by-products'.

In September and October 2004 Cassini continuously observed Saturn for several weeks using eight different filters (CB1, MT1, CB2, MT2, CB3, MT3, BL1 and UV3). The result was a 2x2 image atmospheric movie and (needless to say) lots of interesting images. The images in this and the following posts are derived from a few of these images.

Unless otherwise noted all of the images I used for the color composites I'm posting here are from this sequence of images and were obtained from a distance of 7.2 million km on September 30, 2004.

Here is a 2x2 mosaic of the southern hemisphere:



The overall color is fairly accurate (possibly a bit too saturated), however, small scale features have been sharpened slightly. This image is composed from CB1, BL1 and synthetic green images based on the CB1 and BL1 images. Provided the synthetic green image is properly made the end result is almost indistinguishable from color composites where GRN images are available.

[Bjorn Jonsson]

About 25 years ago the Voyager spacecraft obtained well known false color images of Saturn. This one is a good example. These images were composed by using green, violet and ultraviolet images as red, green and blue, respectively.

As far as I know something similar based on Cassini images has not been publicly released. The image below is composed by using CB3, BL1 and UV3 as red, green and blue, respectively:



The images used for making this false color image were obtained from a distance of 26 million km on May 12, 2004.

This is a version where the color saturation has been increased and small scale details sharpened with an unsharp mask:



Some color fringing is visible, especially near some of the spots. This is due to Saturn's rotation, the three images where obtained over a period of several minutes.

[Bjorn Jonsson]

Like the preceding images, the image below is composed from CB3, BL1 and UV3 images. However, the resolution is much higher:



Color saturation has been increased and small scale details sharpened using an unsharp mask. The limb is somewhat bluish due to Rayleigh scattering. Interestingly, many of the spots (storms) also appear bluish, as well as a large area around the south pole. In addition, lots of small scale details are visible in Saturn's atmosphere.

To compensate for Saturn's rotation between the different images the images were projected onto a seamless, cylindrical map that was then rendered from the spacecraft's vantage point.

This also made it possible to check what Saturn's south pole would look like from directly 'below':



As before, color saturation has been increased and small scale details sharpened using an unsharp mask.

That's it for now. I may post more images later. There are thousands (or tens of thousands) of spectacular PDS images just waiting to be processed .