STEP BY STEP
1 Copy the body parts
Open cockerel.jpg and zebra.jpg into Photoshop CC. Go to the cockerel image and grab the Lasso tool then drag a rough selection around the head. Hit Cmd/ctrl+c to copy, then go to the other image and Cmd/ctrl+v to paste your selection.
2 Position the head
Go to Edit>transform>free Transform. Drag the corner of the bounding box while holding Shift to resize the layer. Fine-tune the positioning until it fits with the lower image. If needed, go to the Layers panel and reduce the layer opacity to help you see how the image match up.
3 Make a precise selection
Get the Quick Selection tool and paint over the red bits of the head to isolate. Click ‘Select and Mask’ in the tool options, then up the Radius to 15px and paint over messy bits of the edge with the Refine Brush tool to fix selections. Set Output: Layer mask and hit OK.
4 Clone out the overlap
Highlight the bottom layer, click the new layer icon in the Layers panel to add an empty one. Grab the Clone tool then set ‘Sample: Current and Below’ in options. Hold Alt and click to sample a source from the backdrop, then paint to remove the clashing zebra head.
5 Perfect the blend
Highlight the layer mask thumbnail on the top layer then grab the Brush tool and hit D to reset colours to black and white. Zoom in close and perfect the edges of the layer – either by painting black to hide or white to reveal. Hit X to switch between the colours.
6 Add a shadow
Highlight the layer below the chicken and add another new layer. Grab the brush tool and paint with black along the edge of the chicken head where it meets the body to add a shadow, then lower the layer opacity until it looks natural. Make tonal tweaks to finish off.