Our campus celebrates the tech-fest over the next 3 days, 17-19 March. Visit QUARK'07 website for more.
We are organising an Astronomy Workshop for participants, where I will present one talk. I am also involved with Image Processing contest, where students will be grilled for their skills with images.
Friday, March 16, 2007
Thursday, March 15, 2007
Modified algorithm for UVIT frames
Make a table (dimentions 4x1000) for Poisson statistic. x-axis is average photons at a pixel Pij and Y-axis is the number of photons. X-axis values range from Pij = 0.001, 0.002,... 1.000, in steps of 0.001 (1000 values). Y-axis has 4 values, which are equal to probabilities of number of photons incident = 0, 1, 2, 3.
For example: at x = Pij = 0.1, the four values (corresponding to probability of 0, 1, 2, and 3 photons incident on that pixel) are P0 = e-0.1 (= 0.9048), P1 = 0.1 P0 (= 0.09048), P2 = 0.01 P0/2 (=0.0045242), and P3 = 0.001 P0/6 (= 0.0001508).
For a given framek, find a random number R equally distributed between 0 and 1. For each pixel
For the next frame, compute a new random number R and repeat the above steps again...
For example: at x = Pij = 0.1, the four values (corresponding to probability of 0, 1, 2, and 3 photons incident on that pixel) are P0 = e-0.1 (= 0.9048), P1 = 0.1 P0 (= 0.09048), P2 = 0.01 P0/2 (=0.0045242), and P3 = 0.001 P0/6 (= 0.0001508).
For a given framek, find a random number R equally distributed between 0 and 1. For each pixel
- If R <>0, then number of photons for that pixel = 0.
- If (P0 + P1) > R > P0, then number of photons = 1; and if (P0+P1+P2) > R > (P0 +P1) then number of photons is 2; and so on.
For the next frame, compute a new random number R and repeat the above steps again...
Monday, March 12, 2007
UV image simulation from Galex
This is an algorithm to generate frames from Galex image.
You make a table (dimentions 4x1000) for Poisson statistic. x-axis is average photons at a pixel Pij and Y-axis is the number of photons. X-axis values range from Pij = 0.001, 0.002,... 1.000, in steps of 0.001 (1000 values). Y-axis has 4 values, which are equal to probabilities of number of photons incident = 1, 2, 3, 4.
For example: at x = Pij = 0.1, the four values (corresponding to probability of 1,2,3 and 4 photons incident on that pixel) are 0.1, 0.035, 0.002, and 0.0005.
For a given framek, for each pixel
You make a table (dimentions 4x1000) for Poisson statistic. x-axis is average photons at a pixel Pij and Y-axis is the number of photons. X-axis values range from Pij = 0.001, 0.002,... 1.000, in steps of 0.001 (1000 values). Y-axis has 4 values, which are equal to probabilities of number of photons incident = 1, 2, 3, 4.
For example: at x = Pij = 0.1, the four values (corresponding to probability of 1,2,3 and 4 photons incident on that pixel) are 0.1, 0.035, 0.002, and 0.0005.
For a given framek, for each pixel
- Find a random number R equally distributed between 0 and 1.
- If R > 0.1, then number of photons for that pixel = 0. If R > 0.035, 0.002 and 0.0005, then number of photons incident on that pixel are 1, 2, 3.
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