MOC images, though high quality, rarely decompress from IMQ into a quality high enough for detailed viewing. The compression artifacts, data drops, and streaking inherent due to the nature of the camera and data transferral methods are actually only a slight hindrance. They can be removed from the images with a little finesse and the appropriate software. The results of these images when done properly give us a close up look at the surface of Mars so far unparalleled by any instrument ever sent. Care given in processing will bring out great visual detail.

I will go over the general steps I use in decompressing, destreaking, clarifying, contrast adjusting and optimizing the MOC images into a file size manageable quality JPEG. These are simple yet effective, tried-and-true techniques and tools. The results speak for the validity.

Software Used

• NASAView 2.5.8
      Standard all purpose PDS decompressing and image viewing software.

• Mocomatic (by Robert Shepherd)
      Visual basic program utilizing an effective destreaking algorithm for use with MOC images in .raw or .img format. (for Windows)

• Jasc Paint Shop Pro 7+
      All around great image control and enhancement tool.

Processing Steps

1. Decompression
   Decompress the .imq or .img file using the NASA software of your choice. NASAView 2.5.8 is recommended. A preliminary visual evaluation of the image can be done now. Proceed to save it as a GIF for further processing.

2. Dealing with Dropouts
   Open this GIF in your favorite imaging software. (Paint Shop Pro 7 is mine, but Photoshop or equivalents are suitable.)
   • If the image is error free, and clear of data drops (bands that run across the images in black/white strips or "fuzz") save it as a .raw file, and note the image size (***x***** pixels)
     [or]

   • If error bands or other data drops are visible further steps must be taken as follows:
     • Using the select tool set on rectangular shape, surround the errors and cut these damaged areas from the darker albedo images, or

     • flood fill color them in solid black on higher albedo images.

     • Save these corrected images as a .raw image and note the image size (***x*****)
     
     You lose those areas, but they are damaged and unusable anyway. Take care to get them all. Left there they spread through the histogram and distort the destreaking and adjusting process.

3. Mocomatic Destreaker
   The .raw image is then taken into the Mocomatic destreaker, which will prompt for the image size, and upon entering this it will open the image and give you histogram and comb filter strength options.

   It will work automatically with preset configurations with a click of the "Ask Robert" button. The output is generally a wonderfully streakless, or reduced streak slightly contrast adjusted and stretched .bmp image complete with configuration files for reference.

   Robert did wonderful job on the automatic settings, but it will accept manual settings on both the histogram and comb filter.

   With a little familiarity great results can be obtained by evaluating the image and adjusting the settings based on the observance of it's particular needs. I usually set the comb filter .03 higher than what is automatically detected, and leave the histogram settings automatic unless I detect that better results would be obtained by manual adjustment. In this, experience and observation of results teaches the finer nuances.

   The resultant image should be very much improved now, and is ready for fine greyscale adjustment and file size optimization.

4. Final Enhancement
   The resulting destreaked .bmp image is then opened in PSP7. Using it's clarifying, contrast & gamma adjusting, sharpening and various other filters gently, the full realization of the greyscale potential begins to take good shape, with the surface details becoming clearer and better defined as the albedo differences defined more sharply.

Human eyes seem to have the ability to recognize at best about 12 different shades of grey. Best results are had when the average of these 12 shades is distributed evenly across the image.

Care must be taken not to overprocess. This final touch is the step that is the hardest to achieve proficiency in. Careful trial and error with the sequencing of these processing steps is the best exercise.

Image properties ascertained through individual observation of the images, and processing applications supplied based on the specific demands of each image's particularities are things that the processor has to weigh and balance.

The desired and attainable result is wonderfully clear Mars images of the type needed for detailed surficial observation, adequate for the science of putting equipment down safely and maximizing our discovery of this wonderfully beautiful world.

K.L.