Photoshop Tips – How to Change Colour of Objects and Colour Correction

A big client has just carried out a photo shoot on their product range… But wait! That photo is too dark and the product is in shade… That one is in direct sunlight! The products are all different shades of colour. We want them to look consistent! How do we fix that?…
This is common task faced by image retouchers… Below is one method for completely changing the colour of an object, but which can also be used for colour correction to a specific CMYK breakdown and ironing out tonal variations. The program used is Photoshop, and the walkthrough uses a photograph of a car for demonstration purposes… We’ll change it from its original silver colour to red.
Colour-Correction-Original-Image
1) Go to the tools palette and select the ‘Pen’ tool. Use this to trace the shape of the bodywork.
The aim is to have a path containing only the area of the image whose colour you want to change, meaning other details can be left unaffected by changes to the colour made later.
Note: Instead of the pen tool, you could use the magic wand tool to make a selection. I find the pen tool gives more control in most cases.
1-pen-tool
2) This is how the finished path looks. Use the ‘Path Selection Tool’ to select the entire path.
Colour-correct-path-selection
3) In the ‘Paths’ palette, click the small ‘Load path as a selection’ button.
Colour-Correction-load-Path-As-Selection
4) Making sure you are on the layer which contains the image whose colour you wish to change, navigate to: ‘Image > Adjustments > Selective Color’
4-image-adjustments-selectiveColour
5) The colour of the car in my picture is silver, so in the ‘Selective Color’ palette, I select ‘Neutrals’ from the drop down. Select whichever colour in the list matches your image’s current colour (eg. if your car was blue, you would select ‘Blues’. This lets Photoshop target pixels with the selected colour and allows you to alter them.
6) I want to make my car red. Let’s imagine that I have been asked to change the colour to red with a specific CMYK breakdown of C:0%, M:100%, Y:100%, K:0%. I now position the paint dropper cursor over an area of the silver car that is not in shadow and not too brightly lit by the ambient light. I chose an area of the front bumper on the car.
Note: Clients will often want their product images adjusted to a specific colour, often with a provided CMYK breakdown. This method works well for colour correcting to a specified colour. Alternatively, it is possible to use ‘Image > Adjustments > Hue/Saturation’ to quickly change the colour of the car to red, but using selective colour lets you be more precise.
4a-image-adjustments-selectiveColour
7) Now, with the paint dropper still positioned over the bumper, watch the info palette. My starting values are C:44% M:51% Y:49% K:11%. I want to adjust these to C:0%, M:100%, Y:100%, K:0%. Using the Tab key to cycle through the % text boxes for Cyan, Magenta, Yellow and Black in the ‘Selective Color’ dialog box, you can adjust the values using the Up and Down arrows on your keyboard. Hold ‘Shift’ to adjust in increments of 10%.
8) In this way, I set Cyan to -100%, Magenta to +100% and Yellow to +100%. In the info panel, my new colour values for that area of the bumper are now C:0%, M: 95%, Y: 90%, K:0%. That’s pretty close to our desired value for red! You can now get even closer by changing the Color to ‘Reds’ in the dropdown box and adjusting the sliders further, until you get to your desired colour displayed by the info panel.
5-red
9) Some areas of the paint still have a silver tinge to them. To get rid of this, create a new layer above your base layer. With your selection still active, fill with red C:0%, M:100%, Y:100%, K:0%. Now set the layer to ‘Color’ and the opacity to 50%. Getting closer!
6-red-layer
7-red-color-50
10) The highlighted areas of the bodywork look too light in comparison to the lowlights. This can be corrected by adjusting the Exposure of the image. With your base layer and your marquee selection active, navigate to ‘Image > Adjustments > Exposure’
11) The image shows the values used. These will vary for every image, but essentially, I reduced the exposure and tweaked the Offset and Gamma Correction values until a natural looking colour and tone was achieved.
8-gamma-correction
12) We could stop here. But, adjusting the exposure will have slightly altered our red values. So, again, with your base layer and your marquee selection active, navigate to ‘Image > Adjustments > Selective Color’. Select ‘Reds’ from the drop down, and while watching the ‘Info’ panel, adjust the slider values using the up and down arrow keys until the values for CMYK in the info panel are or are very close to C:0%, M:100%, Y:100%, K:0%. That’s it!
10-total-red
13) Here is the finished image, compared to the original. Plus a blue one for good measure 🙂
11-3-cars
I hope this post is useful to image retouchers! There are probably many ways to achieve the above, but the method above always works reliably for me.
 

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