Comments on: Episode 069: Burn and Dodge

By: Rolf

Rolf — Thu, 11 Jun 2009 21:55:12 +0000

Two episodes a day – that has to be heavy overload! And you’ll get withdrawal symptoms, if you don’t slow down and hit the raw feed.

I have not checked your calculations – but they look right. I only use mathematics when there is no other way to understand this – I included it here to get different ways of understanding into the video. For Burn and Dodge only one thing is important: white brightens up, black darkens down. You control the amount by opacity of the brush (a tablet is very nice here) or by using different shades of grey. Predicting the outcome is difficult, I check by looking at the result while editing the image.

This method is not my idea – like most of the stuff I know about GIMP and image manipulation I learned it somewhere and can’t recall where.

By: John

John — Thu, 11 Jun 2009 16:53:19 +0000

I discovered “Meet the Gimp” last month and have watched every episode until this one. Of course I plan to watch the others. They’re great! This one was, for me, the most interesting by far. It really tested my understanding of the underlying model.

Specifically, I am struggling to understand how the layer mode affects the resulting image.

Suppose the background image “midtone” area is a solid medium gray (808080) and that we have perfectly isolated this area with a white mask (the mask is black everywhere else). Now suppose we paint one white (dodge) and one black (burn) pixel in the midtone layer. Naturally these must be painted where the mask is white in order to affect the result. According to the formula for overlay mode given in the linuxtopia reference, the result should be an arithmetic average of screen mode and multiply mode since the “weights” B/255 and (1-B)/255 both equal 0.5.

Consider the white pixel. Screen mode would turn the result pixel white, and multiply would leave it unchanged. So the result will be the average of medium gray (808080) and white (FFFFFF), or A0A0A0, a light gray.

Consider the black pixel. Multiply mode would turn the result pixel black, and screen would leave it unchanged. So the result will be the average of medium gray and black, or 404040, a dark gray.

It took me an hour to figure this out, and I do not even have 100% confidence in my analysis. Perhaps someone will spot an error. With realistic background colors, like the ones in the image you used in this episode, screen and multiply are weighted unequally, and my mind simply cannot predict the result.

I guess that am looking for a non-mathematical mental model of layer modes that will enable me to predict results. Maybe such a model does not exist, but if you have one, it would be great if you devolted an episode to explain to us how your mind works. For example, how did you come up with this technique? Or is everything simply done by trial and error?

Thank you for providing a fantastic resource to the Gimp community.

By: Paul

Paul — Tue, 20 Jan 2009 10:09:04 +0000

Another way would be a duplicate layer for dodging and another one for burning (using the dodge and burn tool). Then I wouldn’t use overlay, I would use Darken only (for burning) or Lighten only (for dodging).

By: Norman

Norman — Fri, 31 Oct 2008 09:24:54 +0000

There is an old saying – ‘There is more than one way of killing a cat’ ( apologies to animal lovers) – and often the simplest way is the best.

By: Rolf

Rolf — Thu, 30 Oct 2008 16:08:59 +0000

@peterson: Thank you, I’ll contact you.

You can use a lot of modes – the results vary. Overlay enhances contrast when you use a copy of the image. Here you use black or white and not the image.

@Norman: I use mostly the simple way I showed in the past. Here I just wanted to show how to emulate the option in the tool.

By: Norman

Norman — Thu, 30 Oct 2008 14:44:53 +0000

I think that the first example you gave of dodge and burn was towards the end in episode 10. The technique used there is similar to that shown here but differs in some respects and is much simpler but I suppose not so effective. Time moves on and so does one’s knowledge and experience and it is most interesting to do what I have just done use the ‘time machine’ and go back and look at the past.

By: peterson

peterson — Thu, 30 Oct 2008 10:39:03 +0000

Thanks for the show!
Is “Overlay” the preferable mode for dodging and burning in GIMP or just a matter of taste (depending on the image). Hard/Soft light should work as well? I thought “Overlay” was to enhance contrast?
You notice me being a bit confused

Concerning the “Teamwork”: what about using a Google Calendar for coordinating the concerted effort. I am no expert on this, but as far as I know several people can edit and see it.

I do not post regularly, but visit the forums quiet frequently and would be glad to help and kick spam out.

By: Martin

Martin — Wed, 29 Oct 2008 19:45:59 +0000

This is my first comment on your site, even though I have watched many of the videos. Great work which is very much appreciated. I agree that using layers is a more controllable method of dodging and burning, however, having seen your tutorial I thought i would experiment with the dodge and burn tool. It certainly is powerful and great for playing around with. I think I will use it in the same way as one of your previous posters, on a separate layer.

By: Rolf

Rolf — Wed, 29 Oct 2008 14:47:40 +0000

Yes, there are a lot more possibilities with this. I wanted only to show in a quick way how to emulate this option in the tool.

One could even work with “weird” curves and get very strange effects….

By: Ger

Ger — Wed, 29 Oct 2008 14:39:18 +0000

In addition you could use some technique of Charles Cramer;
Tonal Selection.

http://www.luminous-landscape.com/tutorials/Cramer_Selections.shtml?main_page=product_info&cPath=20&products_id=173

Before creating a layer with Highlights, midtones or lowlights you should examine the zone to dodge or burn using the curve tool.
Move the cursor over the image with CTRL-left click and look which colors are used

By: AmZer

AmZer — Wed, 29 Oct 2008 13:53:17 +0000

Nice technique! you could also just change the brush mode without creating a new layer but it’s probably wiser to use layers.

By: Fornit

Fornit — Wed, 29 Oct 2008 06:52:34 +0000

Hi,
nice technique you show in the video. You’re right, the burn and dodge tool is best for fast changes on small parts of the picture. Even for that cases I use a copy of the layer. For changing big areas of the picture, I sometimes use a copy of the layer in a different blendmode and a layer mask, or several copys in different blendmodes, each for another area of the picture. But your technique with the three layers is very good. I will try that.
Greetings
Fornit

By: Inkscaper

Inkscaper — Wed, 29 Oct 2008 01:31:46 +0000

“Teamwork is when everybody does what I say”