Photo Collage from Color to Black and White Effect

Firstly, start by finding a stock photos that you can add the effect to. A couple of good resources to find free stock photos are: stock.xchange and DeviantART. First of all find the photo of interior with sofa and another one will be the photo of the dog. If you want to use your own pictures, feel free to use it and experiment with composition. Open the photo of the dog and try to separate the silhouette from the background with Polygonal Lasso Tool.

Now, copy selected part of image with Ctrl+C, then open the picture with sofa and paste (press Ctrl+V) copied fragment from the first photo to the second.

After that reduce copied fragment about 30% horizontally and vertically

Bulldog does not look realistic in the background. We should fix this problem. Right click on the current layer in palette thumbnails and apply such Blending Options:

This layer style should be saved on the new layer as separate effect to have an opportunity to work with in future. Apply Layer > Layer Style > Create Layer to divide this layer style from the main layer. Go to the new separated layer with drop shadow (under the current layer) and use the Smudge Tool to transform it a little bit as on my picture below.

After that apply the Eraser Tool and a soft round brush to clear shadow, which is located behind the dog outside floor.

Go to the layer with dog again and apply following Blending Options to it:

See the result on the picture below:

After that get out the Burn Tool (Brush: 50 px, Range: Midtones, Exposure: 30%) and obscure the back of the dog, which is in the shade.

I think, It will be better to add the text, get out the Horizontal Type Tool and write out the text using green (#dcea78) color.

Ok, merge all layers in one and duplicate with Ctrl+J. Then we need to desaturate copied layer. We can do this by using Image > Adjustments > Desaturate.

Now we have black and white photo and one color photo under. I'm going to mix two of these photos in the next way: select the Eraser Tool and use some soft round points to clear black and white image partly.

Then use the Custom Shape Tool to add different sizes white animal prints.

Now, merge all of prints in one layer and change layer mode to Overlay. Also set up opacity to 20%.

I'm sorry, but tutorial is over. Hope, you had fun with it and learned something new. Good luck!