Custom White Balance after the Shot?

[NorthernLight]

Hello everybody,

after endless month I got lucky last night and took some shots with my EOS450D and a CLS clip filter.

I hadn´t had any chance to produce a shot of a whitecard with the filter in to set the Custom Whitebalance but thought it might be possible to do it afterwards.

Today I took such shot and now I am looking for an option to reset the WB for all shots with the information contained in the picture of the whitecard.

Is there an option in Canons Digital Professional or a trick to do it later in CS2 i.e.?

Please don´t tell me I have to live with the blue images.... (8hours imaging down the drain).

Cheers

[bmitchell82]

Photoshop you can run a Auto Levels

Alternitively you can do it manually with greater control

open the histogram up of the R G B channels
open up Levels (Image --> Adjustment --> Levels)

you have 3 options RGB combined, and the individual channels align the histogram so they all drop under each other. You can also use this technique for a DPP stretch.

Hope that helps oh and for the record i havn't bothered with WB/Custom white balance for ages unless im doing terrestrial work which makes post processing a whole lot easier. Astro is different as you are stretching the data out to fill the full 16 or 32 bit gamut.

[mswhin63]

I know with whitebalance issue with my planetary shots that I use a feature called "Colour Balance" to align the colours correctly. I believe deepsky Stacker you have to do it manually apart from that not sure.

[Octane]

Max,

Even if you set the white balance in Digital Photo Professional after the images have been taken, there isn't much point in doing this as your astrophoto pre-processing software is not going to honour the change.

Unless you plan to set white balance, export as 16-bit TIFFs, then stack the TIFFs instead of RAWs, there's not much point.

Also, using auto levels as mentioned above, is just about the worst thing you can do.

Auto levels, auto contrast and auto colour all do very different things, and they revolve around the blacks and whites in the image.

We massage our data so much, that white balance really isn't an issue.

H

[NorthernLight]

Hi Brendan, Malcolm&Humayun,

after some investigation I found a way to change the WB afterwards.
Up to 3 WB values can be registered in DPP and applied to every picture.

I usually convert all RAW´s to 16bit TIFF´s because DSS doesn´t have the right codec´s for the EOS450D - and the 400D codec´s produce worse results than the TIFF´s.

The blueish tint in the images taken with the CLS filter is hard to overcome afterwards and I find it much easier to use the correct WB in the first place.

To demonstrate what I mean I have attached the below shots.

Thanks for your very fast answers!

Cheers

[Octane]

Max,

Yep, the other thing you can do is just make your appropriate changes to one image, right-click on it and select Copy Recipe to Clipboard. Then, select all your other images (Ctrl+A), right-click on any of them and select Paste Recipe from Clipboard. Click Yes/OK, and, all your images have the same white balance/edits applied to them.

I use this for weddings/portraits where the images were taken under the same/similar lighting conditions.

H

[bmitchell82]

DPP i don't like, it is far to harsh and you don't have good control over the image. Im sure there will be people who disagree with me but its personal taste.

Have you installed the Drivers for your 450D onto your PC though EOS Utilities? as i have never had a issue with getting things to work once i installed the drivers as it has the raw codec embedded in the install.

Plus working with RAW helps you with your colour and processing in Photoshop essentially giving you more colours to work with (H, please correct me if im wrong at any stage here). Plus when your stacking your images with Flats, Dark and Bias reduction frames working in RAW will give you a much better result.

Learning basic processing skills is the key stone to your image coming good. look up Ken Crawfords utilities on his web page there is hours of good information with respect to Photoshop and processing with astro photos.

Just for interest i have given a little bit of balance to your image hope you don't mind.

Brendan

[NorthernLight]

Hi Brendan,

thanks for the ´balance´ add to the shot- looks great and you seem to got more detail out of it. I wonder how you manage to get that? especially out of a 55kb JPG:question:???

Yes, I installed it all on my PC and Picasa i.e. can open the .CR2 shots but not Photoshop CS2. DSS can open them but I have to choose the 400D from the menu as there is no 450D. But the sendor of the 400 is smaller and I assume it has some more differences that in effect reduce the quality of my shots.

PS: pls don´t bother about the M42 any more, it was actually a miss shot that I posted for demo of difference: I accidentially gave my eq6 the wrong time on setup and when I had slewed to the horsehead, through the finder I saw some nebulosity, centred it and took a test exposure that lasted the time I needed to go back in and get a new beer:P When I was back I noticed that the nebulosity actually was M42...

Cheers

[bmitchell82]

Make sure that you have told DSS the right Bayer matrix RGGB not GRBG, there are a few different settings. That will mess with the image more than anything as the algorithm goes over the whole Bayer irrespective of size.

Its the Levels and Curves iterations that bring out fine dim data that would other wise be hidden. or commonly known as Stretching the data. virutally your taking what is but a pin prick in a 32bit output dropping it to 16bit (thats the amount of colours you are able to use so work as long as you can in 32bit). you then take that same pin prick and stretch it out to fill as much of the 16 bit histogram as you can with out stuffing up the black/white points.

Sometimes its the smallest things that will upset the apple cart.!

No problems about the shot, my thing is that taking the image is 20-30% of the task, processing it the rest. aka ill take 2-4hrs of data and it will take me days to process it properly.

[NorthernLight]

HI Brendan,

after processing the actual target, and considering what you were able to achieve even from a very small file, I am wondering if that is really all there is. So if you have a minute or two; would you mind inspecting the attached file and let me know what can be done to sqeeze out more detail without attracting more noise or processing artefacts?
I used a number of curves and level adjustement layers and a gaussian blur mask to get rid of noise. But beyond what I have attached the horsehead is either bright and detailed with lots of noise or as it is now (medium detail) with low noise. Is there another way?

I´d be grateful for any useful advice...

[Octane]

Hope you don't mind, Max.

I had a quick two minute play in Photoshop. There's a bit of data there.

You need to apply multiple curves/levels applications in subtle amounts.

H

[NorthernLight]

wow, thanks for that. I will try and apply more levels and curves. That looks fantastic.

Cheers

[bmitchell82]

Its not about doing more levels and curves, its about the iterations of how you do them. Little bits at a time my general balance and stretch will take a good 5-6 goes at Levels and a few of the curves Just to start the ball rolling.

Try getting yourself a proper noise reduction program, they are worth every cent you pay for a good one as noise is a major issue with DSLR cameras as they are not cooled.

have you had a look at ken crawfords tutorials yet?

[NorthernLight]

Hi Brendan,

no I haven´t heard of these tutorials so far. I am reading another book: Photoshop Astronomy by R. Scott Ireland. but I have to admit that I only read it when I have new data to process and basically look for certain sections instead of studying the book to understand what it is all about.
My problem is that after 4 or 5 curves clipping occurs on both ends or the histogram fragments at some point.
I will have a look at Ken´s tutorials, thanks for the tip.

Cheers

[Octane]

Max,

If you're clipping after a couple of iterations of curves, then, you're stretching far too much.

Note, I mentioned "subtle" in my previous post. After performing a set of curves, go back, and re-level your colours. This will also help you find where you're clipping.

Instead of watching tutorial videos, the best way to learn Photoshop is by doing. Constantly playing around with menus and settings will reinforce your knowledge. What's the worst that could possibly happen? If you've made a backup of the file you're working on, no biggie. Following other people's methods line-by-line is going to get you stuck in a rutt. Each image will be processed differently to the last. Get a feel for the basics such as levels and curves, then, step into opacities, blend types, selections and masking, then other (slightly) advanced topics such as colour balancing. From there, the basic constructs apply to the majority (if not all) of the other adjustments that can be made in Photoshop. It's not difficult. Get in there and do it!

H

[marki]

Max, H is right and a master of PS. But if you are a ludite like me you may want to invest in CCDstack. All you need to do is select a small part of the background under the colour tab, click set backround --> ok and all of the annoying blue is gone in 2 seconds. More visable detail and better colour balance occur as a result. Playing with levels and curves in PS is a fine art and will take time to learn.

Mark

[NorthernLight]

Hi Mark,

I too think that Humayun is right and I have to spend more time playing with PS. And I think Bredan is right too in saying that I need a pro-noisekiller like neatimage or noiseninja.
I am grateful for the advice and keep progressing slowly into the art, admiring those who achieved hubble-like images and staying far from those who want to become like them in no time.
I just accidentially bumpt into stargazig and the whish to take pictures came with it after some time but I am satisfied with what I got so far and the posts of the pro´s here showed me that there is still potential.
I take it from there and thank you for your advice.

Max

[marki]

Max, CCDstack is not a quick way to become "like them", it just has a function that makes it easy to set white/black points so you can get on with the rest of your processing in PS which I think is what you originally asked for. It has a lot of other great functions as well but that is irrelevent here. You might like to take a look at Adam Blocks website for more info on CCDStack and what it can do. He also offers a great tutorial series (on DVD) based on using PS for processing astro images.

http://www.caelumobservatory.com/

Mark

[multiweb]

Have a look there (http://blog.deepskycolors.com/tools.html). I haven't tried it but there are a few PS plug-ins and one does color balance.

[NorthernLight]

Hi Mark&multiweb,

thanks for the helpful links. I will give it a shot next WE.

Cheers