[X] My Assistant

[manishm1020]

Dear HiRISE experts,

I have obtained .tiff files of HiRISE images taken from PDS. They are all 10-bit data. I would just like to obtain the I/F for each of these images. I basically calculate the I/F from equation: I/F = (gain*DN) + offset. I use the gain and offset provided in the .LBL within PDS for each image. Now the question is - can I use the 10-bit data in the I/F calibration equation? Do I need to convert this 10-bit data to 14-bit data? If I do that, can I basically multiply each DN value by 2^4? If this is not possible, how can I obtain the original 14-bit data? If it is 10-bit data, the dynamic range of I/F for my images in the southern polar dunes (PSP_003386_1080) only spans from 0.09 to 0.2. I have read that frost/ice can approach much higher reflectance values. There must be something that I am missing. If it is 14-bit data, the dynamic range would span 0.09 to 1.5.

Any advice that you could provide, would signficantly help. This has been a bit confusing for me.

Thank you so very much.

-manish mehta

[elakdawalla]

Would the low I/F values you are getting result from the low angle of the Sun? The HiRISE web page for that image says the sun's only 24 degrees above the horizon.