johnpane
Well-known member
I have three questions about the ESD rejection algorithm.
1) Assuming ESD low relaxation is set to 1 (presumably no effect), if outliers is set to 0.3, does that mean:
a) that 30% of the total pixel stack can be rejected by the combined effects of high clipping and low clipping?
b) that 30% of the total pixel stack can be rejected by high clipping and another 30% by low clipping?
c) that 30% of the above-median pixels can be rejected by high clipping, and 30% of the below-median pixels can be rejected by low clipping?
d) that 15% of the above-median pixels can be rejected by high clipping, and 15% of the below-median pixels can be rejected by low clipping?
Option (a) is implied by the tooltip, "The default value is 0.3, which allows the algorithm to detect up to a 30% of outlier pixels in each pixel stack." But this would mean that high clipping would be affected by turning on or off low clipping, which would certainly be an undesirable effect.
2) Is the ESD significance test applied to:
a) each individual potential outlier?
b) the entire pixel stack?
Option (b) is implied by the tooltip, reworded here for clarity "0.01 means that a 1% chance of being wrong is acceptable when rejecting the null hypothesis (that there are no outliers in a given pixel stack)." That is, the tooltip implies that the test is all or nothing, either there are outliers that can be rejected or there are not. This would seem to give the user no control over how many outliers can be rejected. If there is one clear outlier with p<.000001, the null is rejected but what other outlier get rejected in this case?
3) What parameter is relaxation applied to:
a) a divisor for the outliers parameter?
b) a divisor for the significance parameter?
c) something else?
I see no hint in the tooltip. But if the answer is (a), how does that interact with the answer to (1) above?
Thank you,
John
1) Assuming ESD low relaxation is set to 1 (presumably no effect), if outliers is set to 0.3, does that mean:
a) that 30% of the total pixel stack can be rejected by the combined effects of high clipping and low clipping?
b) that 30% of the total pixel stack can be rejected by high clipping and another 30% by low clipping?
c) that 30% of the above-median pixels can be rejected by high clipping, and 30% of the below-median pixels can be rejected by low clipping?
d) that 15% of the above-median pixels can be rejected by high clipping, and 15% of the below-median pixels can be rejected by low clipping?
Option (a) is implied by the tooltip, "The default value is 0.3, which allows the algorithm to detect up to a 30% of outlier pixels in each pixel stack." But this would mean that high clipping would be affected by turning on or off low clipping, which would certainly be an undesirable effect.
2) Is the ESD significance test applied to:
a) each individual potential outlier?
b) the entire pixel stack?
Option (b) is implied by the tooltip, reworded here for clarity "0.01 means that a 1% chance of being wrong is acceptable when rejecting the null hypothesis (that there are no outliers in a given pixel stack)." That is, the tooltip implies that the test is all or nothing, either there are outliers that can be rejected or there are not. This would seem to give the user no control over how many outliers can be rejected. If there is one clear outlier with p<.000001, the null is rejected but what other outlier get rejected in this case?
3) What parameter is relaxation applied to:
a) a divisor for the outliers parameter?
b) a divisor for the significance parameter?
c) something else?
I see no hint in the tooltip. But if the answer is (a), how does that interact with the answer to (1) above?
Thank you,
John