I'd like to convert some client logos into a single light grey colour
The logos are in PNG and JPEG formats on a white background.
I know that I can convert the image to greyscale and / or use the channel mixer but it's not giving me the exact colour I need.
Everything the isn't white needs to be
How can I change all colours in an image - except the white background - to a single specified colour?
For examples like the one in your question, you can use a Solid Color layer with a blending mode.
Open the image in Photoshop.
Layers panel, select the circular icon at the bottom to
Create new fill or adjustment layer
Solid Color from the list that opens.
Input the colour you want in the hexadecimal box at the bottom right of the box that pops up and press
OK. You can select the colour through other methods of your choosing, and you can select a different colour later by double clicking on the Solid Color layer thumbnail at any time.
For this specific logo and the colour you want, the blending mode that works perfectly fine is
Lighter Color. Select the
Lighter Color Blend Mode from the dropdown list in the layers panel.
Other logos or a different target colour may require different blending modes, and complex logos or ones with backgrounds may not work with the blend mode method at all. Logos like the one you've provided work perfectly fine though.
You could use the wand tool, 'W', select everything in the logo, change the foreground color to #BFBFBF and hit Alt + Backspace