Grid Pattern on Video Stack

[guillespiers]

Hi everyone,

This is my first post, so I´ll start saying that my english is a little bad (but my spanish is very good ), so please excuse me if there´s anything wrong in my writing!

My name is Guillermo Spiers, and I´ve been doing planetary astrophotography over the last 2 years. A couple of weeks ago, I "jumped" to the webcam world with a new ZWO ASI 174 MC (color). It´s an amazing camera I´m now using it with Firecapture.

My normal capure method is:

- Firecapture

- PIPP (if telescope was to schaky)

- Autostakkert

- Registax (wavelets)

The thing is that my final images look with a green, red, or sometimes grey grid. If you zoom the image, it will be more evident. This happens despite having a good image on firecapture´s preview screen

What is this grid? Are all my videos compromised with this?

I read something about a "Debayer" function which may be involved, but I don´t understand when or how is this affecting my videos.

If I open the AVI files on windows media player, they all look black and white (this is because they´re not debayered... I supose?)

I´ve tried firecapture debayer, PIPP, and autostakkert but I´m still getting the same grid. It´s like the program is messing with the real colors.

I´ve attached 2 pictures as a reference. The "greenish one contains the "grid" that I mentioned, and the "redish" one shouldn´t be red of course

The camera is fine, but I don´t know what I´m doing wrong, please help!

[michael8554]

Hi Guillermo, I'm going to Lima on holiday in October, I'll drop in ...... :->

It's been a while since I've used it, but I have a Philips webcam that is modded to give RAW output.

Part of the processing involved de-Bayering and there was more than one Bayer pattern to chose from.

Your first image looks like what I used to get if I chose the wrong pattern - no colour and a visible grid.

How was  the second image produced?

Michael

Michael

[guillespiers]

Hi Michael! Nice to meet you! You`ll love Lima (specially the food ). Feel free to ask me anything about your trip, maybe I can help you with anything, or recommend you some basic places to visit!

About my problem,

The first green image was a SER file type. I think firecapture selects it as a default extension when you choose 16 bit colour.

This was the log file of that capture:

FireCapture v2.4  Settings

------------------------------------

Camera=ZWO ASI174MC

Filter=L

Profile=Moon

Filename=Moon_195901.ser

Date=270615

Start=195901.651

Mid=195916.658

End=195931.665

Start(UT)=005901.651

Mid(UT)=005916.658

End(UT)=005931.665

Duration=30.014s

Date_format=ddMMyy

Time_format=HHmmss

LT=UT -5h

Frames captured=3212

File type=SER

Binning=no

ROI=1376x864

ROI(Offset)=188x278

FPS (avg.)=107

Shutter=2.063ms

Gain=200

USBTraffic=60

SoftwareGain=10 (off)

AutoExposure=off

WRed=60

Gamma=40

HighSpeed=on

WBlue=100

Brightness=97

Histogramm(min)=17

Histogramm(max)=228

Histogramm=89%

Noise(avg.deviation)=n/a

Limit=30 Seconds

Sensor temperature=35,5 °C

****************************************

I don`t remmember very well, but I think the second image was done with the Debayer turned "on".

This were the settings:

FireCapture v2.4  Settings

------------------------------------

Camera=ZWO ASI174MC

Filter=L

Profile=Moon

Filename=Moon_213809.avi

Date=270615

Start=213809.434

Mid=213824.499

End=213839.564

Start(UT)=023809.434

Mid(UT)=023824.499

End(UT)=023839.564

Duration=30.130s

Date_format=ddMMyy

Time_format=HHmmss

LT=UT -5h

Frames captured=3256

File type=AVI

Extended AVI mode=false

Compressed AVI=false

Binning=no

ROI=1216x928

ROI(Offset)=348x142

FPS (avg.)=108

Shutter=5.677ms

Gain=200

HighSpeed=on

WRed=60

Gamma=50

WBlue=100

AutoExposure=off

USBTraffic=90

SoftwareGain=10 (off)

Brightness=97

Histogramm(min)=27

Histogramm(max)=188

Histogramm=73%

Noise(avg.deviation)=n/a

Limit=30 Seconds

Sensor temperature=35,2 °C

Video on both cases looks fine, the colors are very natural, but they`ll get messed up when I stack the frames.

[guillespiers]

I`m processing the second video again...

I`ll use PIPP for a start. This is the first screen that loads when I grab the AVI file.

Should I choose Yes or No?

[RCompassi]

Click YES

[RCompassi]

(or Sí in your case, hehe)

[cgarry]

One thing to note is that colour ASI cameras do not do any colour balancing when in 16-bit mode.  This means that you will get a strong colour tinge like in your red moon image in you opening post.   I suspect that your red moon image is correctly debayered but showing the colour tinge because of the lack of colour balancing in 16-bit mode.

You can fix this in PIPP (if PIPP has debayering enabled) by setting this option:

* Processing Options Tab->Set Histogram White Point to 75% = Enabled.

This balances the red, green and blue levels to give a balanced white image.

You can also just process the 'red' frames as they are and correct the colour levels in the final image.

I would say the grid is caused because the wrong bayer pattern has been selected.

Cheers,

Chris

[guillespiers]

Thanks a lot people! I`ve been messing a little with my images, and I`m sure that I made a mistake when I recorded those two moons up there . Chris, you are right, maybe I clicked the 16 bit checkbox with the red moon.

I fixed the red moon image by debayering it in PIPP and stacking it again in autostakkert (which was also forced with the same pattern: RGGB).

This means that I can fix any image I took from that day? Only by changing the debayer pattern?

I read that ASI cameras work best with RG pattern... So I just saved it in Firecapture.

Only the greenish moon hasn`t been fixed. I cannot clear that grid from it. I´ve tried a lot of debayer pattern combinations, but it`s worthless... 

I`ll try another round this weekend on the mountains, hopefully I`ll get some good frames!

Thanks!

[glowingturnip]

hi Guillermo,

Yes, that's definitely the bayer grid you can see in the first one.  I've seen similar things to this if you have the wrong camera or driver selected at capture time, so maybe you need to play around with Firecapture to see which settings produce the gris and which ones don't.

Actually, just seen your settings, so the first one was SER and the second one was AVI, so just shoot in AVI.  The second one doesn't have the grid, and the colour cast is easily fixed with white balance.

Great pics btw

[guillespiers]

Thanks a lot Stuart! Definetly AVI is better!

I´m going to the mountains this weekend! I´m praying for clear skies!