DSS changing bit depth?

[stefski]

Hi All,

Was trying to process some images last night. I stacked my 16bit TIFF files on DSS, as I have done many times before. The resulting image looked as they often do....I then tried to open it in GIMP. Usually it tells me it has to change the bit depth from 16 to 8 bit and I click OK. However, last night I kept being told that my stacked file was 32bits and, in one case 48 bits:icon_eek:, and that the program couldn´t open the file at all???!!! I checked all the file lists on DSS, they all say the images are 16bit. However, when viewing the properties of the resulting stacked image, it did indeed say 32bit:icon_scratch:. Does anyone know why this is happening all of a sudden? It wasn´t happening before!

Cheers,

Stef

[stefski]

Bump??

[perfrej]

I never use GIMP and advise you to actually change. 8-bit depth is nowhere near enough for astronomical use. 16 is borderline. In order to avoid scaling errors, many astro-dedicated image editors work with 32-bit floating point format internally, and in that case 16 is enough. You have to take into consideration that each channel has distinct features that need separate stretching and that the term 24-bit gives you just 8 bits per channel.

Pixinsight would be a good candidate to look at.

As for your reported problem, my guess is that either DSS is actually producing the format that GIMP reports to be in the file, or that GIMP is unreliable in its format analysis and reporting.

All the best,

Per

[stefski]

Cheers for the advice , Per....I'll have a look at Pixinsight.

Thanks,

Stef

[stefski]

......200Euro after 45 day trial.....A bit more than 'free'!! Still....worth a thought for the future!

Stef

[JohnC64]

Not sure about your 32bit issue, but I use Gimp to process images. The trick I found was to convert your 16bit tif files output from dss into 16 bit png files. Gimp can process pngs in 16 bit mode. I understand that Gimp will be supporting 16bit tiffs in the next release.

Cheers John

[stefski]

Hi John,

Oooohh! That sounds promising. How do I convert to png?

Stef

[JohnC64]

I use nebulocity (as I use it as my image capture engine) but I guess that any Paint program (Except Gimp!!!) will be able to load the 16 bit Tiff and then do a file Save as .png.

Cheers John