Can't seem to get color images - Pixinsight

[bennethos]

Hi,

Been using a zwo385MC color cam in sharpcap 3.1 , selected RAW16 and saved in TIFF (I know now I probably should have saved it in FITS).
Did 30 frames at 120s and preprocessed everything following tutorials in PI.
But I seem to fail miserably at the LRGB combination. I just don't get any color in my image following the tutorials.
Wondering at this point if I made a mistake recording the images ?
Same problem with deepstacker, no color.

From what I understand they need to have debayering done on them, but I suppose Pixinsight takes care of this using the LRGBcombination process ?

FYI saved some frames in RGB instead of RAW16 and had colour, if I understand debayering is already done when saving in RGB but not optimal.

When I take the properties in GIMP it's not looking too good. (see attach) . It just says it's grey scale, when I put it in RGB in Gimp it stays grayscale.

I must have done something wrong recording in sharpcap I guess ? Is it the RAW format ? There is a choice between 8 and 16... 

 

another update, if I open one of these TIFF files in Fitswork and I do debayering on it I get color !
Why the heck doesn't pixinsight work on the sharpcap zwo generated RAW16 files ?
someone else seemed to have exactly my problem : https://bbs.astronomy-imaging-camera.com/viewtopic.php?f=29&t=7686&start=0

It's all a bit new to me , thx for the advice

 

 

Tried doing a debayer process in pixinsight and get the following error  :
 

Loading target file:

C:/Users/Panasonic/Desktop/SharpCap Captures/PI_Pre-Processed/calibrated/light/cosmetized/_00001_c_cc.xisf

Loading image: w=1936 h=1096 n=1 Gray Float32

*** Error: Unable to acquire CFA pattern information: Unavailable or invalid image properties.

 

* Applying error policy: Continue on error.

*** Error: No image could be demosaiced.

<* failed *>

Loading target file:

C:/Users/Panasonic/Desktop/SharpCap Captures/PI_Pre-Processed/calibrated/light/cosmetized/_00001_c_cc.xisf

Loading image: w=1936 h=1096 n=1 Gray Float32

*** Error: Unable to acquire CFA pattern information: Unavailable or invalid image properties.

 

* Applying error policy: Continue on error.

*** Error: No image could be demosaiced.

<* failed *>

 

 

[Tim]

Havent got time to go in detail, but colour cameras dont do LRGB.  Have a read of light vortex astronomy tutorials and pay attention to the bits about debayering.

[wimvb]

One shot colour cameras output gray scale images in raw format.  In PixInsight the image's window header will show "grey scale". The colour information is contained in the pixel position and the Bayer matrix (rggb, bggr, grbg, etc). Together, this is enough to determine the colour information in each pixel. DeBayeting is the process of converting this information in a colour image. After deBayering, the image's window header will show "RGB".

The stacking process is as follows:

1. Calibration with bias, darks, flats

2. DeBayering

3. Star alignment

4. Integration

If your image isn't deBayered, it will be gray scale after integration, and contain no colour information. LRGB combination only adds lightness (contrast) information to an RGB image, but won't convert gray scale into colour.

Hope this helps

[wimvb]

7 hours ago, bennethos said:

From what I understand they need to have debayering done on them

Yes

7 hours ago, bennethos said:

Pixinsight takes care of this using the LRGBcombination process ?

No

See my previous reply

The error message you get when you try to deBayer in PixInsight, means that the program can't retrieve the proper Bayer matrix information from the file header.

I can check PixInsight later to see how you can retrieve the information.

Could you supply one raw image file?

Later:

Use the DeBayer process (Process | ColorSpaces | DeBayer). Load your tiff files into the process, and supply an output directory and the Bayer matrix information (default is RGGB)

[bennethos]

Thx so much guys, it's my first astronomy session with a 385MC camera in France and my Esprit 100ED !

Here is an image shot in RAW16 in sharcap as requestd, M27

Thank you for giving me the step by step too, will try it now in PI. But do I need to do the step of LRGB at all then or not ? The PI insight book that I bought as well as another book only discuss combining monochrome images that have used filters.

 

_00001.tif

[bennethos]

It works in PI (screenshot in attach) ! I think i must have lost the color properties along the way processing the images as I was following the "monochrome filter" workflow.

1. Calibration with bias, darks, flats

2. DeBayering

3. Star alignment

4. Integration

4. DynamicCrop

5. Color Calibration

6. Gradient correction --> Automatic Background Extraction Process

7. Deconvolution

8. Histogram Transformation Process

9. Histogram adjustment (photoshop, can I do this in GIMP or PI ? )

10. ...

[bennethos]

7 hours ago, Tim said:

Havent got time to go in detail, but colour cameras dont do LRGB.  Have a read of light vortex astronomy tutorials and pay attention to the bits about debayering.

Thx for that site, it contains a proper workflow that I can use reading my book. But again seems to be for monochrome images using filters. Will debayer first then.

[wimvb]

You have a so called osc (one shot colour) camera. The workflow is identical to dslr imaging. This means that you deBayer during preprocessing (calibration, deBayer, alignment, stacking). The image after stacking is then a colour image.

RGB workflow is applicable to mono cameras, where you take 3 sets of exposures, one for red, one for green and one for blue. After preprocessing there are three b/w masters: representing each of the three primary colours. These are then combined into one colour (rgb) image before further processing. This seems more complicated, but there are several advantages.

You should read this book, available from our sponsor:

https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

Btw, I'm in the middle of a move right now, so I don't know when I can have a closer look at the image you provided.

[wimvb]

On 25/08/2018 at 13:02, bennethos said:

It works in PI (screenshot in attach) ! I think i must have lost the color properties along the way processing the images as I was following the "monochrome filter" workflow.

1. Calibration with bias, darks, flats

2. DeBayering

3. Star alignment

4. Integration

4. DynamicCrop

5. Color Calibration

6. Gradient correction --> Automatic Background Extraction Process

7. Deconvolution

8. Histogram Transformation Process

9. Histogram adjustment (photoshop, can I do this in GIMP or PI ? )

10. ...

Suggestion:

Swap steps 5 and 6. Gradiebt removal can affect colour balance.

9 can be done in PixInsight: either use histogram transform or curves transformation. Personally, I prefer the latter for fine adjustments. I only use HT for initial stretch, and to change the blackpoint.

While there may be benefits to going between different software packages, imo it's better to first learn one. This way you keep the full process history (easier to undo and redo), and the colour bit depth. PixInsight works with 32 bit floating point accuracy. Gimp only 16 bit integer, and ps a mix of 16 and 32 bit, I believe.

[wimvb]

Had a quick look at your image (tif). PixInsight can't extract Bayer information. Otoh, you seem to have solved the problem. If you save the raw image as fits, it will be easier to retrieve information from the header (in PixInsight: File | FITS Header).

Btw, was that tif file processed in any way? I applied DBE and colour calibration, and this is the result (no stretch)