FDPiech
5th October 2006, 02:21 PM
A simple masking technique.
Sometimes we want to remove our subject from their environment. Sometimes we want to adjust our subject and not the background. Either way, it's time to learn a little something about making a mask.
There are many, many ways to make a mask to remove your subject from the background. This is not the only one. This may not be the best. However, on the right kind of image, it will allow you to remove your subject in the least amount of steps.
http://www.piechdesign.net/tutorial_img/mask_start_image.jpg
Take this image above for example.
The gray fades down in such a way that the subject starts to get lost in the flatness. What I'd really like to do is be able to adjust the background of the image and the subject of the image separately.
To make our mask, we are going to start by looking at what we already have in our image that we can use as a starting point.
Let's click on our Channels Pallet (usually in the lower right corner under the layers pallet in a default PS setup) and take a look at the different channels of the image and see if one of them will make a good starting point for our mask.
http://www.piechdesign.net/tutorial_img/mask_channels.jpg
What we're looking for is what channel gives us the most CONTRAST between our subject and the background. It's kind of a toss up between the green and the blue channels in this image, but every image is different. I think I'll use the green.
<RIGHT-CLICK> on the green channel, and select <Duplicate Channel> Your pallet will now look something like this.
http://www.piechdesign.net/tutorial_img/mask_pallet_1.jpg
<CLICK> on our new channel to be sure that it is our active channel.
Now that we have a starting point for our mask, we need to start refining it. We want our mask black over our subject and white on our background.
Click -> <Image><Adjustments><Threshold> to pull up the threshold dialog.
http://www.piechdesign.net/tutorial_img/mask_threshold.jpg
It looks a lot like the histogram. If you drag the little arrow in the middle from side to side it will change our image. All values to the left of the arrow will become 100% black. All values to the right of the arrow will be 100% white. Let's pull our arrow to the right until the subject is as black as we can make it while not allowing any black from the background to meet the edge of our subject. Like this:
http://www.piechdesign.net/tutorial_img/mask_threshold_1.jpg
Hey! That's pretty good. We have the subject 100% black, the background is mostly white and the parts of the background that ARE black don't touch the subject.
Let's get rid of that last bit of black in the background.
Set your Foreground Color to WHITE
Pick a reasonable size, soft edge brush from the brush pallet and just paint over those parts of the background that are still black so that our final result looks like this:
http://www.piechdesign.net/tutorial_img/mask_threshold_2.jpg
Ok... Almost home free now. Right now the edges of our mask are very hard and distinct.
http://www.piechdesign.net/tutorial_img/mask_mask_1.jpg
We need to soften them up just a little bit so that we get a good blend between our subject and it's background.
Click <Filter><Blur><Gaussian Blur>
Select a value that just starts to blur the edges of our mask. The value will be Dependant on the image. This image is very small so I used a value around 1.3. Your value will be different. The goal is that the edges of it look like this when you're done.
http://www.piechdesign.net/tutorial_img/mask_mask_2.jpg
That's it! Now we have a clean mask that will allow us to separate our subject from our background and let us do our adjustments on the one without effecting the other.
<CTRL><CLICK> on our new mask channel to make it the active selection the flip back to the Layers pallet. Look at how well our mask selects our subject with the "Marching Ants"
http://www.piechdesign.net/tutorial_img/mask_final_select.jpg
Here is our final image with the background blown out to white.
http://www.piechdesign.net/tutorial_img/mask_final_image.jpg
I hope you find this tutorial useful. I know that I have.
Sometimes we want to remove our subject from their environment. Sometimes we want to adjust our subject and not the background. Either way, it's time to learn a little something about making a mask.
There are many, many ways to make a mask to remove your subject from the background. This is not the only one. This may not be the best. However, on the right kind of image, it will allow you to remove your subject in the least amount of steps.
http://www.piechdesign.net/tutorial_img/mask_start_image.jpg
Take this image above for example.
The gray fades down in such a way that the subject starts to get lost in the flatness. What I'd really like to do is be able to adjust the background of the image and the subject of the image separately.
To make our mask, we are going to start by looking at what we already have in our image that we can use as a starting point.
Let's click on our Channels Pallet (usually in the lower right corner under the layers pallet in a default PS setup) and take a look at the different channels of the image and see if one of them will make a good starting point for our mask.
http://www.piechdesign.net/tutorial_img/mask_channels.jpg
What we're looking for is what channel gives us the most CONTRAST between our subject and the background. It's kind of a toss up between the green and the blue channels in this image, but every image is different. I think I'll use the green.
<RIGHT-CLICK> on the green channel, and select <Duplicate Channel> Your pallet will now look something like this.
http://www.piechdesign.net/tutorial_img/mask_pallet_1.jpg
<CLICK> on our new channel to be sure that it is our active channel.
Now that we have a starting point for our mask, we need to start refining it. We want our mask black over our subject and white on our background.
Click -> <Image><Adjustments><Threshold> to pull up the threshold dialog.
http://www.piechdesign.net/tutorial_img/mask_threshold.jpg
It looks a lot like the histogram. If you drag the little arrow in the middle from side to side it will change our image. All values to the left of the arrow will become 100% black. All values to the right of the arrow will be 100% white. Let's pull our arrow to the right until the subject is as black as we can make it while not allowing any black from the background to meet the edge of our subject. Like this:
http://www.piechdesign.net/tutorial_img/mask_threshold_1.jpg
Hey! That's pretty good. We have the subject 100% black, the background is mostly white and the parts of the background that ARE black don't touch the subject.
Let's get rid of that last bit of black in the background.
Set your Foreground Color to WHITE
Pick a reasonable size, soft edge brush from the brush pallet and just paint over those parts of the background that are still black so that our final result looks like this:
http://www.piechdesign.net/tutorial_img/mask_threshold_2.jpg
Ok... Almost home free now. Right now the edges of our mask are very hard and distinct.
http://www.piechdesign.net/tutorial_img/mask_mask_1.jpg
We need to soften them up just a little bit so that we get a good blend between our subject and it's background.
Click <Filter><Blur><Gaussian Blur>
Select a value that just starts to blur the edges of our mask. The value will be Dependant on the image. This image is very small so I used a value around 1.3. Your value will be different. The goal is that the edges of it look like this when you're done.
http://www.piechdesign.net/tutorial_img/mask_mask_2.jpg
That's it! Now we have a clean mask that will allow us to separate our subject from our background and let us do our adjustments on the one without effecting the other.
<CTRL><CLICK> on our new mask channel to make it the active selection the flip back to the Layers pallet. Look at how well our mask selects our subject with the "Marching Ants"
http://www.piechdesign.net/tutorial_img/mask_final_select.jpg
Here is our final image with the background blown out to white.
http://www.piechdesign.net/tutorial_img/mask_final_image.jpg
I hope you find this tutorial useful. I know that I have.