Topaz ReMask Tutorial
Now that Topaz ReMask 3 has been released, I am posting this brief tutorial of this very useful
plug-in from Topaz Labs. Usual disclaimers apply - I don't work for them or receive any other form
of consideration and blah blah...
This software is available for both PC and Mac and works with Photoshop CS3-CS5 and Elements 6-9.
Thanks to Nancy Bell for letting me use her wonderful shot of the Green-headed Tanager as an
example. This capture is a perfect example of an image that can be "saved" by using an extraction
tool like Topaz ReMask. I'm sure you can find lots of other applications for this plug-in besides
replacing the background. It is very desirable, especially with bird and wildlife images, to be
able to apply noise reduction and other filters to the background only and apply sharpening only to
the subject. This becomes very easy with ReMask. Let's get started... I am using links to the images because there are so many.
http://kerryperkins.zenfolio.com/p798443741/e1569807f
I have opened the image and we can see the problem - the background just has too many issues and we
would like to replace it completely with a different one. As a matter of routine, I always make a
copy of the original layer. You can do this by dragging the layer to the "new layer" icon at the bottom of the layers palette. Add a layer mask to this layer by clicking on the layer mask icon at the bottom of the layers palette. Be sure you click on the image thumbnail of the layer before proceeding. You do not want to have the layer mask selected or the filter won't work. The next step is to select the Topaz ReMask 3 filter from the list.
http://kerryperkins.zenfolio.com/p798443741/e66ffcfe
When the image is opened in ReMask, the entire image shows a green overlay. This is the area that the filter is going to keep. What we want to do is define the areas that we want to delete, leaving only our subject. We do this by using the "compute" brush, which we will use to paint a blue path along our subject to tell the filter where we want it to look for edges. This brush is selected automatically when you open the filter, so you just need to size your brush appropriately and start painting along the outer edges of your subject.
http://kerryperkins.zenfolio.com/p798443741/e12ddd971
Here you can see that I have started to paint around the edges of the bird. I am also going to include the branch, as I want that to be part of my foreground. Notice that there is a message at the bottom of the window that says "Brush over the area that you want to compute." Move the cross-hair part of the brush along the edge to get as close to half background/half foreground as you can. If you stray from the edge too far with your brush, just go back and paint in the part you missed, it will just add to what you have already painted. If you really mess up and want to backtrack, there is good old "control Z" (command Z on a Mac).
http://kerryperkins.zenfolio.com/p798443741/e13e4dad8
Here you can see that I have painted the entire area that I want to define as the edge of my mask. Note that I have also painted the area between the feet where I want to eliminate the background.
http://kerryperkins.zenfolio.com/p798443741/e1f6f57d6
We are now ready to make the initial mask. Go to the tools panel on the left and select the red bucket. We will use this to fill the areas that we want to cut with red.
http://kerryperkins.zenfolio.com/p798443741/e126f44a5
Here I have clicked on the background above and below the bird. All that is left is to click in the area between the legs. Notice that there is a message at the bottom of the window that says "Fill over the area that you want to cut". Now that we have defined our background and foreground, we can click on "Compute" (in the tool panel on the left) and let the software work on the mask.
http://kerryperkins.zenfolio.com/p798443741/e143ea04
Here we see the initial results of the mask creation. As you can see, the mask isn't perfect and could use some cleaning up. This is where ReMask really shines. They have given us tools to fine-tune our mask and make quick work of doing so. If you look at the tools on the left of the screen, you will see some brushes. I'm only going to discuss the basic brushes, but will briefly describe the singe and dual color brushes. There are three basic brushes - "keep" (green), "cut" (red), and "compute" (blue). The meanings of these brushes are pretty clear - paint with the green brush where you want to keep more, the red brush where you want to cut more, and the blue brush where you want the software to try harder at finding the edge. I mostly use the keep and cut brushes to refine the mask to look like the original subject. The secret is to use a small brush and just make little strokes in the general area that you want to refine. The software understands that you are pointing out an area where there is too much (use the red brush) or too little (green brush) white in your mask.
You are not limited to looking at your mask while you refine, the five buttons at the top of the window - "Image", "Trimap", "Mask", "Keep", and "Cut", allow you to look at those views and the effect of your last brush stroke on each. In the next image you will see that I have cleaned up the mask around the legs and feet considerably. It only took a few quick strokes to do this.
http://kerryperkins.zenfolio.com/p798443741/e1ad11f0a
While this technique is difficult to describe in words, you can see a quick video of the process in the center video on this page - http://www.topazlabs.com/remask/ . Remember that larger brushes make larger changes and smaller brushes make smaller changes. You use the red brush where you see white in the mask that doesn't belong and the green brush in areas where there should be white but isn't. Once you have your mask refined to your liking, click the "OK" button in the lower right of the screen. You will be returned to PS with a new layer added to the stack, as shown in the next image.
http://kerryperkins.zenfolio.com/p798443741/e2f7eef3
The new layer will have the original image along with an added layer mask. This layer mask is the one you created in ReMask. The great thing about doing this with a layer mask is that you can also edit the mask with any of the editing tools in PS if needed. (If you run the filter on a layer without a layer mask, the result will be a new layer with only the "keep" portion of your trimap.) If you have any artifacts left over on this new layer, e.g., if you have unmasked original background showing anywhere, you can simply use the eraser tool to remove any misbehaving pixels in the top layer.
Ok, the whole point of all this was to add a new background, so I opened one of my "generic backgrounds" that I make from time to time and keep around in my collection. These are very easy to make when you are in the field, especially if you have a long lens on your camera. Simply set the focus for minimum focus distance and shoot into some distant foliage or other interesting colors. You will get a nice soft blurry background that looks just like bokeh, because it is... Here is the one I used:
http://kerryperkins.zenfolio.com/p798443741/eec8d2f
It is nice if your new background image has more pixels than the one you are working on, as you can move it around under your mask layer and find the best look for it. You simply open the file, select all, copy it, and paste it into your project. PS will put it on a new layer at the top of the stack. Just move it directly under your new masked layer and here is the result:
http://kerryperkins.zenfolio.com/p798443741/e1c90304e
Just a note about other uses of the mask. If you didn't have a separate layer already, as I did here, you can create new layers with just the background and just the subject. If you select the original layer (or the first copy under the mask layer) then "control click" (command click on a Mac) on the mask that you created, you will see the mask area selected in your layer. From there you can invert the selection and save the selection as a new layer. This will be your background without the subject, which you can make adjustments to independently.
I hope this wasn't too long-winded... I wanted to give you a good overview of how this tool works and how simple it is to do amazing extractions in PS. The other brushes that I didn't discuss are the single and dual color brushes. These can be used to help extract difficult features (like feathers!) from the background by restricting the software to looking at one or two colors in the background. There are more extensive tutorials on the web, and there are some very good YouTube videos that you can search for. I hope that you will give this plug-in a try, it is well worth the money in my book.
