PI changes image dimentions

[Horwig]

Pixinsight reports the Raws generated by my 5d3 as 5920x3950 pixels, but when I take these RAW frames and integrate them as XISF, it then reports the size as 5792x3870, what's going on?

 

Huw

[Horwig]

After some more research, I think I can answer my own question, here's a resampled CR2 as imported into PI, (I've applied histogram transformation to give it some life):

There's a huge dead band top and left of the RAW image, it must be cropped off by PI when it processes files.

As a different question, has anybody ever attempted to process a meaningful daylight image in PI, I tried to process the test chart above in PI to match what Ps made of it and failed miserably.

Question is, I suppose, does that matter in AP terms?

 

Huw

[IanL]

The cropped areas are the optical black areas. These are pixels that are physically blocked from incoming light, usually by the sensor manufacturer. They are used as part of the calibration process on-camera, e.g. to measure the accumulated dark current and correct for it.

As for processing daylight images, PI uses DCRAW to extract the files which is used by many normal photo applications too. There are settings in PI to adjust how it works (most importantly setting the white balance).

After that you would debayer and proceed from there. Some processes that are mainly astro related are useless, everything from calibration through stacking to linear processes are not much use if any. Anything you would use after stretching to non linear could potentially be useful for daylight images, but it is not Lightroom or Photoshop.

[Horwig]

Thanks Ian, yes the black areas make sense as the areas the camera software uses for calibration of the sensor, wasn't expecting to see them in the CR2 RAW in PI though, I expected all software to crop them out, on my mono astro camera that certainly is the case.

I've been experimenting recently with going back to my DSLR for widefield astro work, having gone across to mono many years ago, and I was finding that I could achieve smoother and more pleasing results in the DSLR widefield milky way shots by not following the usual AP workflow, but by using lightroom to create non linear Tiffs before transfering to PI for registration and integration, compared to bringing linear RAWs directly into PI.

I attempted to process the RAW image of the test chart above in PI, and could not achieve a neutral, well balanced image when compared to the same RAW file viewed in picture viewer, but again, does any this matter in astro work?

 

Huw