Image Quality Issue

[Bigfoot 9907]

Hope you guys and gals can help me. After using a DSLR without any issues I am currently using a Starshoot G3 CCD camera. I took a series of Lights, Darks, Flats and Bias of M101. The lights were unguided at 80 seconds with about 40 subs. However, when I calibrate and stacked them in Maxim DL i get horizontal lines going across the final image which are very visible on close up.

I have enclosed a screen shot.

Any ideas?

Many Thanks

Surinder

[michael8554]

Wrong matrix for the de-Bayering perhaps?

Michael

[Oddsocks]

Hi Surinder,

I had similar problems trying to process a set of G3 colour subs in Maxim DL for someone else last year.

looking at your zoomed image with blue background and green stars it suggests the wrong bayer pattern and interlace has been used to debayer the frames prior to alignment and combination.

I seem to recall one of the generic camera CMY bayer patterns worked in Maxim DL but the camera specific one in Maxim did not for some reason, I think the one that worked for me was one of the Meade camera patterns but can't remember for sure which one.

Try running your stack again but using one of the other available CMY interlace camera versions in Maxim.

If you still have problems then try the Orion software that came with the camera and move the output image across to Maxim for post combination processing, or download the free software Deep Sky Stacker and throw your subs in there for a try.

If you still get nowhere then put your subs into four separate folders, light, dark, bias, flat, put them in a dropbox folder and post the download share link back here and I will put them through my copy of Maxim DL, I still have DL.5 and DL.6 on a virtual windows partition of my Mac so wouldn't take too long.

I will be busy for the next four or five days, got an O.U. tutor assignment to complete and submit by Friday so no rush and It might be a few days before I get back to the thread so dont think I have forgotten, just will be busy trying to get this old head round ionic and covalent bonding, moles and avagadro's constant!!

Dropbox link is here if you don't yet have an account:

https://www.dropbox.com

William.

[Bigfoot 9907]

HI Oddsocks, thank you for the reply, I did try experimenting with different bayer patterns. There was no Bayer pattern for the G3. As for DSS, the strange thing is, the Lights would stack with only the Darks introduced. However, when I introduced the Bias frames or Flats as well, then I got a warning message saying that  one image will be stacked. I tried stacking in Orion Camera studio, but the program kept crashing. The lights were non guided and I used 81 second exposures. I also used a moon glow filter.

Maxim DL was the only software that allowed me to calibrate using all frames.

Anyway, please find the link for the calibration files

https://www.dropbox.com/sh/6rlxm8pmrd2t3vq/AABPj3BnxlF_jUWxtSATCvZba?dl=0

Many Thanks

[lensman57]

HI Oddsocks, thank you for the reply, I did try experimenting with different bayer patterns. There was no Bayer pattern for the G3. As for DSS, the strange thing is, the Lights would stack with only the Darks introduced. However, when I introduced the Bias frames or Flats as well, then I got a warning message saying that  one image will be stacked. I tried stacking in Orion Camera studio, but the program kept crashing. The lights were non guided and I used 81 second exposures. I also used a moon glow filter.

Maxim DL was the only software that allowed me to calibrate using all frames.

Anyway, please find the link for the calibration files

https://www.dropbox.com/sh/6rlxm8pmrd2t3vq/AABPj3BnxlF_jUWxtSATCvZba?dl=0

Many Thanks

In DSS use CMYG 04 pattern for the matrix. If your stars are not round due to bad tracking or focus DSS could throw a wobbler. Also untick the " use median noise reduction " under the part where you choose the  star threshold, it may help. 

A.G

[Bigfoot 9907]

Thanks Lensamn, I am undeed using CMYG 04 pattern. The weird thing is, if I do not add the flats or bias frames, DSS will stack almost all my light frames. As soon as I introduce the flats or Bias, it tells me only one frame can be stacked. A bit of a head scratcher.

[PeterCPC]

Is it the colour G3? I had one of these once and the only way I could get it to work was using the associated Orion software but following the instructions for the mono G3.  Never took flats or bias etc so can't help on that.

Peter

[Bigfoot 9907]

Yes is it. The camera itself is good. Not too impressed with the software though.

[Oddsocks]

Hi Surinder,
 
I have finished with the O.U. tutor assignment for today, after ten hours felt that was enough.
 
Have completed a run through of your image set this evening and have posted the MAXIM DL sequence for you below with images at each step.
 
Before running through the process just be aware that the final outcome is not that wonderful, but also not bad considering that M101 is a faint target and needs lots of long exposures, which you will struggle with at the moment because you are not guiding, but it gives you a taste of what is possible.
 
Colour in M101 is quite muted and will need many more, longer exposures and very well tracked images before it starts to become apparent.

There is a strong colour cast in the final image that I can not remove without enhancing the noise, with better subs showing a stronger signal to noise ratio the image would have stronger, more natural colour.

Noise in the final image is quite pronounced, just down to the short exposures, on a guided mount I would typically go for 6 to 10 minute subs and the final image would be much quieter as a result.
 
As most of the subs showed some tracking error I selected not to reject any subs from the stack otherwise no frames would have been stacked, but when you run through the process yourself you can play with the rejection criterion and you might find you can get a better image with just a handful of the best images used in the stack, I didn't want to spend too much time fine tuning and will leave this for you to experiment with.
 
I have posted a couple of 'rough and ready' final images processed in Photoshop, one adjusted for levels and noise reduction only and one for levels, noise reduction and HDR toning, but as stated above I could not bring too much out of the source data because the background noise level is quite high.
 
The MAXIM published workflow suggests calibrating the light frames before debayering, I have always debayered first and then calibrated but don't really know which way is best so for this run through I have followed the recommended MAXIM workflow, calibrate, then debayer, then stack.
 
My memory was correct, the correct camera choice in MAXIM DL to debayer the Orion G3 colour is the Meade DSI.
 
So here is the process, not a great result but I hope it is easy to follow and useful to you for future processing runs, I have purposely used the American spelling for color so as to match the MAXIM convention, if any questions then add another post to the thread and I will try to respond when I get a chance (being a busy week ahead it might take a while).
 
William.
 
Step 1
Select from the Menu bar:  Process > Set Calibration
 

Step 2
In the Set Calibration window select 'Bias' from the drop down menu and then 'Add Group'

 
Step 3
Highlight the new Bias group and at the bottom of the window click 'Add'
In the new window that opens navigate to the Bias files folder, select all Bias files and then click 'open'

 
Step 4
Repeat Step 2 and 3 to create the group 'Darks', add the darks files to the darks group, then create the group 'Flats', add the flats files to the Flats group

Click ok to save the completed calibration set

 
Step 5
Open all the lights files on to the Maxim desktop

 
Step 6
Select from the Menu bar: Process > Calibrate all

 
Step 7
Select from the Menu Bar: View > Batch Process Window

 
Step 8
Press the red 'Record button' in the Batch Process Window, leave the Batch Process Window open

 
Step 9
Select the first of the lights frames on the open desktop so that it is highlighted, in your case this was "Image1L81"
Select from the Menu Bar: Color > Convert Color
Select from the camera choice menu "Meade DSI"
Press OK to close the Convert Color window

 
Step 10
In the Batch Process window press the black button to stop recording.

 
Step 11
In the Batch Process Operation window tick the box against the process now visible "Color,  Convert Color
In the Batch Process window there should be a blank pane open to the right called "Process Queue", if it is closed press the two '>>' symbols at lower right to open it.
In the Batch Process Window below the blank Queue pane click 'Images'
Do not select 'Add All' as you have already debayered the first image, instead highlight all the lights files with the mouse, then navigate to the first file already debayered and deselect only that file in the list ('Image1L81')
Press OK to move all the selected files into the Process Queue pane

 
Step 12
In the Batch Process window press the 'Play Sequence' button, thats the button with the two right facing triangles
The Color Convert window will automatically open and will display the first debayered file from the Batch Process Queue
In the Color Convert window click the OK button to accept the debayer process, wait a few moments and the Batch Process will open the next file and the Color Convert window will reopen with the next file to be debayered, just click the OK button in the Color Convert window and keep clicking each time the next file appears until all the files in the Batch Process Queue have been debayered, a strike through line appears in each file name in the process queue when the Color Convert process is completed.
When the Batch Process is complete clear the files from the Process Queue pane and Clear the Color Convert Process from the operation list, close the Batch Process window

 
Step 13
Select from the Menu bar: Process >> Stack and click 'Add Files', select all debayered files on the desk top
Ensure that 'Auto Calibrate', 'Color Convert' and 'Make Pixels Square' are not ticked
Select 'Quality' tab and ensure no rejection criterion are selected for this particular batch, normally you would set some rejection threshold
Select 'Align' tab and choose 'Auto Star Matching" from the drop down list of alignment protocols, chose which file to use as the reference image if you do not want to use the default, first in the list
Select 'Combine' tab and choose 'Sigma Clip' from the 'Combine Method' drop down list
Select 'Linear' in the 'Normalisation' drop down list
Press 'Go" to stack images.

 
Step 14
Save the stacked image 'Group1', or whatever name it has been given for this stacking run, as a FIT file in your chosen output folder or desktop, then save it again with a new name e.g. 'Group 1 Duplicate1'
This is the file you now work with and if anything goes badly wrong you can go back to the original 'Group 1' file, duplicate that and begin again.
Close all open files on the Maxim desk top and then reopen the file 'Group 1 Duplicate 1' to begin with gradient removal and color balance

 
Step 15
Select from the Menu Bar > Filter > 'Auto Gradient Removal' this runs automatically without a new window opening

 
Step 16
Select from the Menu Bar > Color > Color Balance
In the Color Balance window click 'Auto" in the 'Background Level' box
Click 'Auto' 'Full Screen' below the 'Preview' pane
Use the 'Screen Stretch' controls to better visualise the image
Now click with the mouse anywhere in the main image to sample the foreground colour and set the colour balance
You will need to click on a part of the galaxy that is not saturated or noisy, I chose one of glowing features in the spiral arm, you can repeat click as many times as you like anywhere in the image until the color looks about right, you will need to repeatedly readjust the screen stretch as you do this, bit of a bug bear in Maxim that it does not keep the setting constant with each new sample.
Click 'OK' once you are happy with the color balance.

 
Step 17
Select from the Menu Bar > Filter > Wavelets
Adjust the Wavelet sliders to suit, You won't be able to use too much because of the noise in this particular image.
When happy click ok to save

 
Step 18
Now at this point you can go on trying different processes in Maxim to try and improve the image and I leave this up to you, for the purpose of this post I exported the image as a TIFF file and made two attempts at improvement in Photoshop with levels, noise reduction and HDR toning.
Select from the Menu > File > 'Save As' and when exporting the image from Maxim as a TIFF, deselect the tick box 'Auto Stretch', click the 'Manual Stretch box to open the 'Manual Stretch' window, (Note: this is not the screen stretch window), and adjust the black level and mid point correction just wider than the main histogram peak, then save with 16-bit-Int selected in 'Size Format' and 16-bit (0 -64K) set in the output range of the 'Stretch' window.

 
Step 19
You're finished with Maxim, now import to Photoshop for further tweaking
If you want to process only in Maxim then at the 'Save As' stage, choose to save as Jpg and adjust the manual stretch black point and mid point sliders to taste and then save with those settings, then the jpg should open looking the same in any photo application you might have.

Basic Levels and Noise Reduction adjustment in Photoshop:

 

Levels, Noise Reduction and HDR Toning adjustment in Photoshop:

 

 
Step 20
Go for a beer and put you're feet up.....don't be too disheartened by you're first attempt, it takes lots of practice with everything going just right in guiding and atmospheric conditions before the images jump out of the screen at you!
 
Hope this helped, best of luck.

[Bigfoot 9907]

Thank you so much Oddsocks for taking taking time out and helping. This will help out a lot of people, not just me. A quick question to get the image from Step 14 to Step 15, did you use the Digital Developments filter?

Many Thanks

[Bigfoot 9907]

I have processed the image in Photoshop. Clearly noise was a major issue and the short exposures (unguided) didn't help. Clearly the image has been over processed and is not the best M101 picture in these forums, but it's amazing how much detail can be obtained by image processing.

Once again, thanks for your help Martin.

[Oddsocks]

Bigfoot 9907,

Quite like your processed version, as you say, its amazing what can be revealed with a bit of digital alchemy!

I did try digital developement but felt it showed the background noise too strongly so I did not include it for my run through with your data.

Just think what might be possible with better tracking / guiding.

William.