Resizing a fits file?

[Gasman]

Hi folks

I have a library of bias and dark fits files all size 1391 x 1039 pixels taken using Windows software. Last night I used a new version of Ekos with my Linux laptop and all the flats and lights have come out at 1392 x 1040 pixels and my spectroscopy software has spit its dummy out and doesn`t like the size differences, is there anyway of resizing either the darks and bias or the flats and lights to the same size please?.

Failing that I`ll have to make another library of darks/bias using Ekos.

cheers

Steve

[andrew s]

If you can work out which edges the extra row and column is on you can crop your new frames. You might be able to do this by looking at  a hot pixel.

In the long run new calibration frames will make life simpler.

You may get issues that the cropped files are at a higher bit depth after the crop depending on the software you use but if you save in the original format you should be fine. 

Regards Andrew 

[vlaiv]

You can use ImageJ (open source) to do any kind of manipulation on fits.

But in this particular case not sure if it will work - I mean it will work but will the result be satisfactory. There are couple of approaches:

1. Actually resize the image - best done if bias / darks were resized by Windows software

2. Given that bias / darks have single column / row removed from top or bottom / left or right side - you need to establish if this is the cause of wrong size (my bet is on this option) you can

a ) just insert blank row/column

b ) copy adjacent row/column to missing one

Worst option is to mix the two - image was resized and you add column/row, or vice versa, column/row was removed and you resize image.

HTH

[andrew s]

I would not advise a resize as it will interpolate the new values. This will invalidate the calibration.

Regards Andrew

[Gasman]

Thanks guys,the thought of cropping a hundred fits files individually makes me cringe, I guess a new library is best.

Cheers

Steve