Properly Exposing With Layer Masks in Photoshop

Layer masking... layer masking is an incredibly handy thing to know, for every photographer. Layer masking can be used well for many things but what I will cover is using it to properly expose an scene with unbalanced lighting. this requires you take at least two photos of the same scene with your camera in the very same place, so this requires a tripod.

I will be using this shot of my backyard for the example. which has incredibly harsh shadows while the sky and clouds are nicly lit and colored by the sunset.. so this would require a graduated ND filter...... or... layer masking in photoshop.. much cheaper

AS you can see The top image is properly exposed for the sky and the bottom image is properly exposed for the back yard (all the greenery) its a bit over exposed but not too bad.

So this technique of layer masking requires photoshop I am using CS5 but it is the same process for the older versions.

1. load your images into PS

2. Drag the images into the same document so that they are both 2 separate layers

3. So first make sure that you take note of which image is on top of which. Then apply a layer mask to the top layer. to do that you will click the tiny button in the bottom right hand corner which has a white circle inside a grey square, located to the right of the button which says "FX"

 

Its kinda hard to find so here's a screenshot of it..

4. once you have clicked that a layermask will be applied you will be able to see it appear in the layers window to the very right of the layer you applied it to.. does that make sense i have a screenshot showing what it looks like a little later on.

5. So heres the key part, which takes some patience and careful movement of the paint brush tool. so select the paint brush tool and make sure the top layer with he mask is selected. set the color of the brush to black, and paint over the part of the image which is not correctly exposed. the black paintbrush will act as an eraser and erase what you paint revealing the image below. so only paint what is not correctly exposed on the top image, but is on the bottom layer.. this is probably super confusing the way im explaining it, but heres a screenshot. you can see in the layer mask all that black against the white background is the part which i have painted over.

So this is a screenshot of the image after i had applied the layer mask and used the black paint brush to reveal all the properly exposed foreground which is much under exposed in the original top image.


6. once you have painted all that you need to, to touch up I recommend setting the brush opacity at 30 - 40 and a fairly small brush size and painting around the edges of the part which you just painted.. this allows for a smoother and cleaner transition of colors and light in the image.

FINAL IMAGE.. i didn't not the best job of painting on the layer mask, but you get the point...

If you have ever seen images which are black and white with a single colored part to it... this is the answer to how that's done. all you need to do is duplicate your layer by right clicking the layer in the layers window and clicking duplicate layer.. then change the top layer to greyscale, then paint in black over which ever part you would like to be in color.. boom done. pretty simple. Once you get this down it can have so many uses, and its not cheating by any means its just compensating for natures way of providing unbalanced light in such scenes...

Creating an HDR...

HDR.. or High Dynamic Range. High dynamic range means that the photo has a very broad dynamic range of luminances, from lights to darks in a given photo. This allows for the entire image to be properly exposed (thats just a simple definition) photos can be quite spectacular when done correctly and not overcooked (in my opinion). although creating an HDR can turn a series of rather unappealing photos into a very colorful - sometimes unrealistic looking - and properly exposed picture, Its does take some conscious planning when you go out and shoot if your planning on creating an HDR out of your shots. By conscious planning, I mean: finding an interesting and colorful subject and scene, planning your exposures and of course keeping your camera completely still during the multiple Exposures. Now I have to say you are able to take a single properly exposed image and adjust the exposure in Lightroom or Photoshop afterward to make one over and one under exposed, However when doing landscapes I have found it to be much more effective to Shoot all the different exposures there rather.

Now The most common purposes of HDR are..
1. To create a properly exposed image of a scene with very unbalanced light. i.e. Looking directly into the sunset over an ocean.. the sunset can not be properly exposed if the Water is too (unless your using a 10 stop ND Graduated ND filter) or a daylight image with intense dark shadows..
2. Boosting colors, and luminance and creating a very unique and almost unrealistic scene. this is probably the case with most HDR's that you will see. The photo can be realistic looking or very unrealistic looking (which im sure you have seen examples)that is all a matter of preferance and controlled during the tone mapping process which i will explain later

Now... For the How to.

1. When your going out to take photos use a tripod is probably the most important. while HDR programs can compensate for slight moving objects and ripples like clouds and trees blowing in wind Your entire image will be messed up if the camera gets moved too much between exposures. 

2. Probably the most helpful thing I have learned is to take more than 3 exposures, while an HDR requires 3 different exposures (1 under exposed, 1 properly exposed and 1 under exposed) It is always a good idea to start out at least 5+ stops under exposed and take a photo every stop you move up until about 5+ over exposed.. So say properly exposed is 1/320th start at 1/40th and take a shot every time you move up one or 2 stops until your at maybe 1/1000th. While choosing your exposures check the objects in your image to make sure that all the parts get properly exposed throughout the series of images (if that makes sense) ill explain more about that later.. Also it is very important you don't adjust your Aperture between exposures, only your shutter speed. Changing your aperture will change the Depth of field and make your photo look very focally un-balanced.

3. Choose your images assuming you shot multiple exposures do not Do any editing to them at this point.

4. Now for the HDR creating part.. I use Photomatix pro because it is by far the most powerful and easiest to use of all that I have tried. Photoshop Cs4 and Cs5 both have HDR software as well, but i don't have much experience with them.

Some free HDR Software is in the links below. I have only had experience with qtpfsugi, and was very satisfied with it!

Essential HDR
Qtpfsugi A.k.a Luminance HDR

 Over Exposed. 1/40th

Under Exposed 1/500th

Properly exposed 1/160th

5. Generating the HDR and then tone mapping it is the final step. Here is a quick set of screen shots showing you the combination process and how it looks after tone mapping. To access the "tone mapping" option on Photomatix you click the HDR tab, the same one you click to add your pictures and "generate your HDR"

Make sure to select "reduce ghosting artifacts" in the initial "generate HDR" screen. After all the tone mapping is done you will end up with a beautiful HDR...

 

All Those exposures were combined and then tonemapped in Photomatix pro to create this final product, as you can see with this HDR I was able to properly expose the Sunset and the entire foreground grass and trees. This would have been nearly impossible in a single exposure with out an expensive graduated ND filter. Now you are able to use layer masks in Photoshop and properly expose this image with 2 exposures, but making an HDR is much more simple and plus creates such an effect which is unachievable by layer masking.. I hope to create a layer masking tutorial soon here too, since that is a Very valuable thing to know.

Hope this was helpful!!
if you have any further questions dont hesitate to shoot me an email..

Thanks for checking this out.