Step 1: Fix the colours
The first step is to correct the overall colour before bringing back details. Create a duplicate layer and call it Working. We want to turn the yellow back into white. In the Layers palette, click on Add New Adjustment and add a Photo Filter adjustment layer. Select the Cooling Filter (80).
Step 2: Looking for white
Increase the Density until the blouse turns as near white as you can get. This should be about 30% though it isn’t even. Select the Paintbrush tool with the foreground colour of black. Set the Opacity to 15% and use a fairly large brush with 0% Hardness. Select the mask itself.
Step 3: Remove some blue
Make one broad sweep over the background area to reduce the blue look to it. It’s then worth reducing the brush Opacity to 5% and doing a second brush over the background, and include the hair as well. Finally, make another application on the left and top right side.
Step 4: Pull back highlights
Press Cmd-E to merge the adjustment layer. Create a duplicate of the Working layer; call it Detail. Go to Image > Adjustments > Highlights/Shadow. Select More Options. Set Shadows to 0%. In Highlights, set Amount to 30%, Tonal Width to 70% and Radius to 80px. In the Layers palette, click on Add Layer Mask.
Step 5: Mask the background
Select the Paintbrush on 33% Opacity, black foreground, and paint on the mask in the background areas to brighten them back up. Once the background is brighter again, press Cmd-E to merge this layer with the one below. Then create a new duplicate of the Working layer and call it Dark spots.
Step 6: Remove dark dirt
Zoom in and select the Clone Stamp tool. Set Mode to Lighten at 100% Opacity. Now move around the image, sampling from nearby and with one click, remove the black spots. This will leave the area around the spot unaffected. Where the spots are on the subject, sample from an area that looks identical.
Step 7: Gentle on the skin
Best practice is to do the background first as you can use faster brush strokes. When tackling black spots on the skin, be careful where you sample from. It has to be a source that matches the brightness and texture of the target area. Only the spot will be removed, but you need to be consistent.
Step 8: Bottom of picture
The bottom of the picture has the most dirt so it’s important to sample from the same brightness area. Also, the picture darkens next to the skin in the right corner. When treating this area you end up painting over all of it. So, when cloning up to the edge of the skin, set brush Hardness to 80% and Opacity to 90%.
Step 9: Emulsions scuffs
Change the Mode to Darken, restore the Opacity and Hardness to 100% and 0% respectively. Clone from the same side of the head and face and remove the white defects in the hair and on the skin. You will need to reduce the brush size to do the areas around the nose.
Step 10: Darken the hair
We’re going to clone a large section from the right-hand side shortly, but before that some of the hair needs darkening. Create a duplicate of Dark spots and call it Hair. Select the Burn tool and set the Exposure to 10% for the midtones. Brush over the top left side of the hair that is less affected.
Step 11: Replacing the damaged hair
Make a selection around the hair on the right. Stay away from the face, but include everything to the right, all the way down to the bottom. Draw the mask line just inside the central trim of the blouse. This is to replace the damaged left side. Press Cmd-C to copy and Cmd-V to paste.
Step 12: Flip and place
Rename this new layer as New body. Go to Edit > Transform > Horizontal. Use the Move tool to position this new body part on the left. Line it up with the blouse edges. Then press C-A to select all and go to Edit > Transform > Skew. Bend the top-right corner down to make the hair join the original.
Step 13: Mask it off
Press Cmd-D to deselect, then add a mask to the New body layer. Select the Paintbrush at 20% Opacity with black as the foreground colour. Use 0% Hardness. Zoom in to the head and paint on the mask where the two elements join. The trick is to blend them together so it looks natural.
Step 14: Do the join
The join that runs down the middle is easy to blend in because there’s a similar lightness at that point. Also, blend across by painting on the mask where the blouse is to reveal the central trim. Increase the Paintbrush Opacity to 60% for this. Finally, mask over the edge on the left.
Step 15: Final adjustments
Merge the New body and Hair layers together and then retouch any small areas that need cleaning up. Go to the Layers palette and add a Vibrance adjustment layer. Increase both Vibrance and Saturation by around 45 to put some colour in. Add a Curves adjustment layer for a little more contrast.
Bonus Tip: Make it less symmetrical
At this point the image has swathes of hair which fall down the front of the blouse and look completely symmetrical. If you want to spend some more time on the image, one idea is to clone up the left arm, across the top of the blouse and in from the shoulder to remove some of the hair. Use the Lighten blend mode with the Clone Stamp tool for this. Also, cut out hair parts from the right and add them on the bottom of the left, masking a few areas to make it look different and to sit on top of the blouse area.