Fits Resolution after convert from cr2

Software Siril
1

Hi,

I am using cr2 raw files from my canon camera for stacking and while siril is converting them, its adding pixels to the resolution of the images. The properties of the cr2 images tells me, the size is 5184x3456 pixels, which perfectly aligns with the cameras spec sheet (Canon 700D), Siril converts those to 5208x3476 pixel fits images.

In some rare cases I have to mix the two formats and then siril complains about the difference in size. Whats the cause for this behaviour and can I change this through prefernces?

Thanks in advance,

Andrej

2

Which version do you use?

3

The most probable explanation is because we use the raw data of the file.
So this is normal.

4

I tried the actual release and the superb beta. Both of which do this.

5

OK. So this is normal for me.

6

Yes, camera images often have a smaller count of pixel than the sensor. You may crop them with the command line if you want to be sure to get them the same size, see the help for it.

1 Like
7

I will try that.

How did I get to this? Well I took Images with Ekos and APT, saved them as fits and the two programm saved nice fits in 5184x3456. Then because of simplicity reasons I took the calibration frames with the camera and an intervalometer. That made nice CR2s in 5184x3456.

So I copied them together, ran the standard DSLR script using all cal. frames and siril converted the CR2 files to 5204x3476… the lights, which were fits from the start stayed at 5184x3456. And now its complaining about the difference in size.

Question ist, will cropping with siril remediate the problem while keeping output quality? I mean, if the calibration frames don’t align properly anymore with the lights, they are pretty meaningless. What do you think?

8

Indeed, it’s not easy… Often, bad flat frames are worse than no flat correction. I would assume it’s centered, but maybe it’s not even that simple… If you have spare time you might try it, you never know…
It’s strange that Ekos and APT don’t get the same image size as siril though.

9

That may depend of libraw version?
If there is no black pixels all around the image, that means that Siril is right ;).

10

Well, i´ve tried several conversion apps like irfanview, Affinity Photo, Photoshop now and all of them convert the CR2s to the original size of 5184x3456.

So Siril is doing something different from the others. Version 0.99.4 Win10 64bit.

By the way, an awesome piece of software, the team did such an unbelievably good job with this. :slight_smile:

11

libraw has changed recently and siril is probably the only software up-to-date. And most other (windows) software do not even use it, so that explains the difference… You may install libraw 1.19 instead of 1.20 to get the previous behaviour, if that’s the actual cause.