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This tutorial demonstrates how to blend two images using Layer Masks.
Understanding Layers Understanding Blending Modes Understand CS4, CS5 & CS6’s Workspace And Palettes
Undo and Navigation Steps Two ways of undoing steps are from the top menu, Edit then Step Backwards. Alternatively, click a previous snapshot in the History Palette.
Navigate (zoom in and pan) your image using the Navigator Palette,
or the Zoom Tool. 
Activate The Hand Tool by tapping the Spacebar, keeping the Spacebar pressed, pan your image in the usual way. 
An Introduction To Masking Proceed To My Cat And Dog Blend Tutorial Here When you create a Mask, you are isolating part of an image: this means, you can change the isolated area (the cat’s eyes for example) either by applying filters, or by removing the area altogether. The area outside the isolated area is “Masked”, and is therefore protected from change. In my example below-left, I applied a Rectangular Selection Marquee around the cat’s eyes, I then applied the Desaturate filter: and as you can see, the filter has changed just the selected area. In my example below-right, I pressed the Delete Key - and this removed the area inside the Selection Marquee.
This is Masking in its simplest form;- the Rectangular Marquee has Masked the outside area, subsequently protecting it from changes.

Now, if I Step Backwards - and apply the Selection Marquee around the cat’s eyes - then Invert it: when I apply the Desaturate filter - or press the Delete Key; the area outside of the Selection Marquee is effected, and the area inside is protected (masked).

Photoshop Masks are stored in Alpha Channels; and Mask Channels are Greyscale Raster images - as such, they can be edited like any other image. Areas painted with Solid Black are protected from changes, and are not editable, and areas painted Solid White are editable. Additionally, Masks contain pixels that can display 254 Shades Of Grey - (256 including Solid White and Solid Black); therefore, for varied opacity - apply shades of grey (as opposed to Solid Black or Solid White); this fades - or blends your images. The levels of grey correspond to levels of opacity, or masking. Solid White pixels show underlying layers; Solid Black pixels hide underlying layers; and Grey pixels show varying amounts of underlying layers - the darker the grey, the more the underlying pixels are Masked, (hidden).
Painting With Black, White And 254 Shades Of Grey There are different ways of Masking images: isolating areas with a Selection Marquee is one way, and applying Masks utilising the Paint Brush is another. However, this blending tutorial concentrates on using Layer Masks, which means we will be layering two images - the Cat and Dog images, adding a Layer Mask to the Dog Layer, and with the Brush Tool, we will remove the dog’s face, so revealing the cat from the underlying layer. When completing this lesson the important points to remember are - Solid Black removes the Dog image, and Solid White brings it back. If you remove too much, don’t worry, you can quickly paint with Solid White to bring it back. (Remember, painting with Shades Of Grey removes, or applies pixels - depending on the grey’s intensity).
1/ Lesson - Create A Photographic Merge To work along exactly, you are welcome to download the Start Images Here. Unzip the file and open the cat and dog images onto Photoshop’s workspace.
Note This lesson is an introduction to Layer Mask Blending; to keep things simple, I am working with two photographs; however, you can blend as many images as you wish.
Additionally, all New Layers can be converted to a Layer Mask.
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2/ From the left-side Tools Toolbar, activate the Move Tool .
And drag the Dog Image onto the Cat Image.
Tip Extend your image’s workspace by left-clicking and dragging out one of its corners.
CS4/CS5 Tip: Snap Your Image To The Top Menu’s Horizontal Bar Another way of centralising an image is to snap it to the top (horizontal) menu-bar by dragging your image towards it: as soon as you see a blue horizontal bar, your image should automatically snap to it.
3/ Ensuring the Dog Layer is active: from the Layers Palette, click the following Add Layer Mask icon.
Note To create a Layer Mask you must have more than one Layer in the Layers Palette.
After clicking Add Layer mask, the Layer that contains the dog will change to the following; the white rectangle with black corners, indicates the new Mask Layer. The four black corners that surround the rectangle indicate the Mask Layer is active.
Note The Mask Layer must be active when editing the Dog Layer.
4/ Now, set the Foreground Colour Swatch to Pure Black and set the Background Colour Swatch to Pure White. You can do this quickly by tapping your Keyboard’s D Key, or by clicking the following Default Foreground and Background Colours tab.
Note To paint with Mask Layers, you must set the Foreground Colour Swatch to Pure Black. Click the following Switch Foreground and Background Colours tab if necessary - or tap your X Key.
5/ Now, from the Tools Toolbar, activate the Brush Tool.
And change the Brush to Basic Brushes. To start, choose a Hard Brush with a suitable Master Diameter (Size). These are my first settings - and remember, you will be changing the Brush Size (and its Opacity) - as you work.
Tip Quickly alter the Brush Size by tapping your Keyboard’s Square Bracket Keys, ensuring lower case is active.
Tip Whenever necessary, Zoom into your work using the Zoom Tool. However, bear in mind, when utilising the Zoom Tool, you need to adjust the Brush Tool’s Size according to the amount of Zoom.
6/ From the Layers Palette, left-click to activate the following Layer Mask thumbnail icon.
Remember! Black removes the dog image, and White brings it back.
Note Ensure the (white oblong) Mask Channel highlighted above, is active when editing the Dog Layer - if it is not, changes cannot be implemented to its Layer.
You are ready to paint with black. Therefore, begin by removing part of the Dog Layer - subsequently revealing the underlying Cat Layer beneath.
Note - Blending Techniques - Continue with lesson here! If you reduce the Brush Opacity to - for example, 30%. Painting will remove less of the Dog Layer - as illustrated below. Experimenting with Opacity level is crucial to perfect blending.
Note An alternative way of fading images is by changing the Foreground Colour to (and experimenting with) various shades of grey - as explained at the beginning of this tutorial Here.
Additionally, changing the following Brush Blending Modes provides interesting and useful results.
Lesson Continued The Dog Layer Mask Thumbnail depicts the removal of the dog’s nose by displaying a black spot.
Now, slowly remove more of the dog’s face. Remember, if you need to paint back the dog’s face, swap the Foreground Colour to Pure White by pressing your Keyboard’s X Key.
Tip If you get over enthusiastic with your Paint Brush, or it suddenly develops a mind of its own and shoots off at an adverse angle - as illustrated below.
Simply make White the Foreground Colour by clicking the following (swap) arrows - or by pressing the X Key.
And paint over the mistake. This paints back areas that have been removed in error. 
7/ Now, ensure the Foreground Colour Swatch is set to Pure Black, and continue removing the dog’s face. To be able to reposition the cat layer; (first activate the cat layer), then from the top menu, choose Layer then choose New then choose Layer from Background, there is no need to name this layer, click OK.
The Cat Layer will change to the following.
You are now able to activate the Move Tool and reposition the Cat Layer, (after first activating its Layer in the Layers Palette).
8/ Remember to reactivate the Mask Layer.
And continue painting with Black (or White) depending on whether you are removing (or reapplying) the Dog Image; swapping the Brush Size and its Opacity - as needed.
9/ Perfect Blending When using Layer Masks, I find the best way to blend transition lines - as highlighted below; is to reduce the Opacity of the Paint Brush, as previously mentioned Here.
Additionally, experiment with different Blending Modes.
Now, continue changing the Brush Size, and remove (and reapply) the Dog Image, as you work.
Tip Applying the Blur Tool (with a very low Strength) can blend the contrast between images.
Tip - Resize The Cat Image To reduce the size of the cat’s face; first activate its Layer, and then from the top menu, choose Edit then choose Free Transform - Ctrl then T. And reduce its size as necessary.

10/ The Cat’s Whiskers Removing the areas around and between the cat’s whiskers requires concentration, and technique. For precision, Zoom into the image, until you can see the whiskers’ pixels - and ensure the full opacity of the cat’s whiskers have been revealed, (paint over them again with Solid Black - to bring them back, if necessary). Now, ensure the Brush’s Opacity is 100%; and ensure the Foreground is Solid White; then reduce the Brush Size, and carefully remove the areas between - and close to the cat’s whiskers.
Note Reduce the Brush’s Size to 1 pixel if necessary.
Tip Isolating the whiskers with a Selection Marquee, and changing the Layer’s Blending Mode, may produce a better blend.
Remember, if you accidentally remove the whiskers, change the Foreground to Solid Black, and paint them back in.

Tip Prior to Flattening the Layers, you may want to save your work as a PSD File.
11/ After you have removed the areas between the whiskers, and you are completely happy with your result: - from the top menu, choose Layer then choose Flatten Image.
Tidy your image by cropping the two images to one size, and save your work.
Final Note You can have lots of fun blending photographs; and depending on your choice of images, the process can be quick - or time consuming; the keys to success are practise and patience.
Wendi E M Scarth - Top of Page - Home.
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