Scale red, green and blue from 0 to 200 percent each to fix colour casts, warm or cool a photo, or isolate one channel. Presets for the common fixes.
Every pixel is a mix of red, green and blue from 0 to 255. This tool multiplies each of the three by a percentage you choose, so 100 leaves a channel alone, 50 halves it and 200 doubles it up to the limit. Because the change is a multiplication, dark areas move less than bright ones and pure black never changes, which is what makes it suitable for correcting colour casts: the cast is strongest in the highlights, and so is the correction.
A 4000 × 3000 photo of a white kitchen taken under warm bulbs comes out cream and orange. Setting red to 90, green to 96 and blue to 114 brings the cabinets back to white and the stainless steel back to grey; the whole pass takes about a second. A scan of a faded 1980s print, which has usually lost cyan and gone reddish, typically wants red at 85 and blue at 110. For a graphic, red 100 with green and blue at 0 gives a single-channel red image at the same brightness as the original red content.
Use it for white balance after the fact, for warming or cooling a batch of photos consistently, and for inspecting or isolating channels. When the problem is that shadows have a tint but highlights are fine, the multiplication here cannot reach the shadows; use RGB Channels, which adds a fixed offset instead. When you want to change colour without touching brightness, Adjust HSL or Adjust Hue are the better tools. If a photo is simply too dark, Change Exposure scales all three channels together.
The three gain sliders run from 0 to 200 percent; the summary at the top of the panel shows the current triplet. Warm and Cool move red and blue in opposite directions by 15 percent, Fix yellow cast is a starting point for indoor lighting, and the Only chips zero the other two channels. Reset returns all three to 100. Output formats and quality behave as in every other image tool; Same keeps the original file type.
How do I remove a yellow or orange colour cast? A warm cast means red and green are too strong relative to blue. Lower red to about 90, green to about 95 and raise blue to 110 to 115, then fine-tune while holding Space to compare with the original. The Fix yellow cast chip is a good starting point for indoor tungsten lighting.
What is the difference between this and RGB Channels? This tool multiplies each channel, so a pixel with no red stays at no red and bright reds clip first. RGB Channels adds or subtracts a fixed amount, which also shifts blacks and shadows. Multiplying is right for colour casts and white balance; adding is right for tinting shadows.
What do Only red, Only green and Only blue do? They set the other two channels to zero so you see one channel by itself, which is a quick way to check which channel carries the detail in a photo or to make a single-colour graphic. Grayscale Image with the Red filter method does something similar while keeping the result neutral.
Is the image uploaded? No. The channel maths runs in your browser on your own device. Nothing is sent anywhere.