batch report pixel values from a sequence of images?

[Phil Hart]

Does anybody know of software that could batch report average pixel value and other pixel stats for a sequence of images?

I want to use an SLR to record variation in sky brightness over the course of a night and between nights. ie. I don’t want to have to open each file and manually enter pixel statistics for thousands of images into a spreadsheet!

The reason for doing this is to get some objective measures of ‘dark sky’ and how it varies. eg with some of my timelapse footage, I think I am starting to see structure and variation in airglow, but I need a bit more evidence to draw the right conclusions.

Cheers
Phil

[Octane]

IRIS.

`stat3 seqname numfiles'

Example:

My 48 RAW files (_MG_001.CR2 through to _MG_048.CR2) are converted to IRIS' native *.PIC format using the decode RAW files option in the pre-processing menu and saved with a generic output name of 'light' so that IRIS outputs _MG_001.CR2 to light1.PIC and so on through light48.PIC.

`stat3 light 48'

Will generate a file titled stats.lst in IRIS' working directory. In this file are statistics with the following structure:

Image Mean Max Min Sigma Median
r1
g1
b1
r2
g2
b2
.
.
.
r48
g48
b48

Image: name of the image
Mean: mean intensity
Max: maximum intensity
Min: minimum intensity
Sigma: standard deviation
Median: median intensity

If you wish to constrain the reported statistics to a particular part of the images, say, for example above the foreground, simply click in four locations in your baseline image which represent the four (x1,y1), (x2,y2), (x3,y3), (x4,y4) coordinates. The values reported in the statistics window can then be used to build the stat4 command which limits the reporting to the square/rectangular window you create.

Note, you must be in x1 (100%) view mode in order to click in the image to generate the coordinates.

Example:

`stat4 seqname x1 x2 y1 y2 numfiles'

`stat4 light 5 4500 10 3700 48'

H

[bert]

Maxim 5 has a quality control window that has Fwhm, colour intersity, roundness and contrast. It does not have the avarage pixel value but the data provided will give you a pretty good indication and you can load a lot of subs quickly (as a batch) for quality checking.

It is found in process>stack and the window that pops up has aquality tab, it is found there.

Brett

[Phil Hart]

thanks Humayan and Brett.. that should give me plenty to work with! :thumbsup:

Phil

[Octane]

You're most welcome, Phil.

IRIS is a wonderful, wonderful tool for astrophotography.

And, the best part of all is its price -- free.

H