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RGB Values to simulate ...


S

SJBlake

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... Black and White photo filters. Hi folks, I'm brand new to this ng and this is my first post. I've been an amateur photographer for 30 years and use Photoshop 7 with a Nikon Coolscan IV as my "darkroom".

I think that the channel mixer is a fantastic tool for creating B&W images from colour ... definitely more versatile than using B&W film (apologies to purists ... my view).

Can anyone tell me or point me to an info source that lists the RGB values that correspond to different B&W filters? Again, if you were shooting B&W it wouldn't be practical (or cost effective) to carry around scads of different filters for different situations, when it can be done in PS.

Sure I can fool around with the sliders (and do) but for better pre-visualization, it would be nice to know the exact values to duplicate filter factors. I've attached an example. This picture started out as a rather nondescript picture in colour ... it looks better this way.

Sorry for the long post. Please let me know if this is generally too long for this ng.

Thanks for all replies.

SB
 
Sorry for the hit-n-run, but I'm in a time crunch right now.

For starters, I recommend getting to know Image > Adjust > Curves.
Intro to Curves by Steve.
Once you start getting the hang of Curves, some really cool things can be done. I'll explain a really cool trick later. BTW, good idea to use Curves as an Adjustment Layer.

If you really want to simulate a lens, I'm sure there is a way. I think it would involve scanning the lens (or getting the lens colour), and then using Blending modes, Apply Image, or Calculations.
 
Here's the pic

My mistake was only looking at the file size requirements and not the pixel dimensions ... this one should work.

SB
 
I got to thinking about it and realized that I'm confused.

Okay, you are starting with a B&W photo. Taken with B&W film.
Or are you starting with a colour photo and looking to change to B&W with PhotoShop?
I believe the latter considering your comment about the purists.

Also, what kind of special lenses are you talking about? From what I remember, there are two basic categories: colour tinted and groovy effects.
I believe the former due to, again, your comment about the purists.

I just want to be absolutely clear about this.
 
Thanks Stroker. Sorry for the confusion ... starting with a colour negative/file. I'm not talking about spec effects filtrations. Talking about the kinds of filters that B&W photogs will use with B&W film eg Wratten #25 Red ... this filter with B&W film will have a specific effect such as turning the sky black.

I want to do the same thing in PS and need to know the filter values for "standard" B&W filters that a photog would use with B&W film. There's a lot of them.

Cheers.

SB
 
Thank you.
I know several approaches to this.
So do some of the others around here.
Unfortunately, I don't have the time right now.

It's a race to get the cookie!
To get a jump start on the competition, read Brush Making. In there, I chat briefly about using Adjustment Layer > HSB and Adjustment Layer Curves to convert colour to B&W with better control.
 
Welcome to the forum SJBlake! :)
Can anyone tell me or point me to an info source that lists the RGB values that correspond to different B&W filters?
Click to expand...
:( Sorry, not specifically... in fact, I did a search and couldn't find anything remotely like what you are looking for. [confused]

In my opinion, it's a matter of playing with the various RGB channels. For example, take a look at these tips http://robertdfeinman.com/tips/tip12.html

I hope that this helps!
 
Thanks Wendy. I have in fact visited this site before and there's lots of good info. I'm not sure that he's entirely accurate in saying that the green channel is equivalent to a Wratten#11 ... maybe it is, maybe it's just close. He also mentions a Wratten #8 Yellow but doesn't give the RGB values.

I know the info's out there somewhere but I too came up blank when I googled it.

Thanks for your thoughtful reply.

SB
 
I'm going to break this down into two different things:
1. Simulating a lens with proper info and application.
2. Tricks for turning a colour photo into grayscale, and/or colour correction.

I've thought about it, and I will not help with #1. I hate to say it, but I'm not going to.

On the plus side, I am more than willing to help with #2.

What say you, SJBlake?
 
Thanks for the offer Stroker ... I already do #2 fairly regularly. I'm looking to refine my overall approach with some of the filtration info I'm looking for.

OTOH I'm always interested in learning new tricks and shortcuts.

SB
 
Sorry for the delay. Getting ready to leave town for a few days, and the girlies aren't very considerate.

One of the better ways is like this:

3. Ad-Layer > HSB and bring Sat all the way down
2. Ad-Layer > Curves and manually tweak contrast in each seperate channel
1. Colour photograph

It is an absolutely wonderful technique. Does wonders for converting fleshtones. If you are not in the mood for Ad-Layer Curves, feel free to try Ad-Layer Brightness/Contrast or something else. Personally, I prefer Curves.

Remember: you can paint on the Ad-Layer. Let's say you have some sky and a building. Well, pumping up the contrast on the clouds destroys the building; and pumping up the contrast on the building destroys the clouds. Just paint!

4. Ad-Layer > HSB with Sat all the way down
3. Ad-Layer > Curves with clouds manually tweaked and painted in
2. Ad-Layer > Curves with building manually tweaked and painted in (basically an inverse of #3)
1. Colour photograph of some sky and a building

Excellant technique to play with.

Gotta go!
 
Stroker: 2. Ad-Layer > Curves and manually tweak contrast in each seperate channel
Click to expand...
Stroker, when you're back, can you explain in further detail how you do this? [confused]

Go off now, get away and enjoy your break! :)
 
Wendy, the 2nd half of Introduction to the Curves Command, Page 2 talks about this.

Add your Curves Ad-Layer.
Using the drop-down, go to Red and tweak
Go to Green and tweak
Go to Blue and tweak
Go to RGB and tweak one last time.
 
Ah yes, thanks for the 'refresher', Stroker! :righton: That's a fabulous tutorial and one that I went through months ago. It seems that I forget more than I learn these days if I'm not putting it into regular practice! [innocent]
 
Hi Blake,

I'm not familure with the use of such filters for black & white so I went to a page where a fellow uses them.

After seeing wht you are talking about at least I think this is, I would suggest this.

Find a photo with the filter(s) applied that you want and open it in photoshop. Then take your eye dropper and sample that color to see what the RGB setting is.

Here is a link to the page I looked at and I must say I never knew this type of photography exsisted.

http://www.coolmint.co.uk/infrared/guide/compare.html

I don't know if this helps or not but I gave it a try. 8)
 
Hi Blake,

I think this is what you are trying to achieve?

26367.jpg

Curves will give this effect too. :righton:
 
Hi Blake,

I did some goofing.

I tried the method I mentioned but I didn't use the channel mixer I used the Curves tool.

I sampled the image above that shows the example of the filter.
When I sampled the filter I got the RGB settings from that.
Then I went into the Curves settings and applied
the numbers to the corrosponding colors.
I placed the numbers in the OUTSOURCE not IN!


R = 210
G = 31
B = 52

This is your original picture.

CoveredBridge2.jpg




This is your image with the RGB settings.

CoveredBridgeWF.jpg


I don't know if this is how it's supposed to look or not like I have mentioned I havenever used filters so I'm just guessing.

Hope this might have helped in some way. :righton:
 
[excited] Interesting link there DigiGuy! I've bm'd it for a good read-through!

:\ Always something to learn around here! ;)
 
May have found what your looking for.

Hi Blake,

In my searching I came across this site, is it what you are looking for?

http://www.silveroxide.com/

Hope this helps! :righton:
 
Another great link, DigiGuy! Lots of great info re B+W photography! Thanks for sharing! :righton:
 
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