The RGB Trap: Why Your Custom Paint by Numbers Won't Match Your Phone Screen

When you upload a photo for a custom kit, you are looking at it on a screen that is backlit by powerful LEDs. When you look at your finished painting, you are looking at pigments reflecting ambient room light. These are two completely different physical processes, and expecting them to match perfectly is scientifically impossible.

Before you begin your custom project, it is crucial to understand the limitations of the medium. Just as you must optimize your lighting environment to see colors accurately, you must also optimize your photo selection for the realities of paint.

1. The Physics: Additive vs. Subtractive Color

The fundamental difference lies in how color is created.

• Your Screen uses Additive Color (RGB): Your phone screen starts as black. To create color, it adds light. It combines Red, Green, and Blue light to create millions of colors. Adding all colors together at full intensity creates pure, brilliant white light. This allows screens to display incredibly bright, glowing "neon" colors.
• Your Paint uses Subtractive Color (CMYK/RYB): Your canvas starts as white. To create color, you apply pigment that subtracts (absorbs) light. A red paint looks red because it absorbs blue and green light and only reflects red back to your eye. The more pigment you add, the more light is absorbed, and the darker the color becomes.

The Takeaway: A screen can create colors that differ in both hue and brightness. Paint can only differ in hue. You cannot paint "brightness."

Figure 1: The "Gamut Cliff." The large outer triangle represents the colors your phone can show. The smaller inner shape represents the colors paint can achieve. The cross-hatched areas (like bright neons) are physically impossible to reproduce with pigment.

2. The "Gamut Problem" Explained

A "gamut" is the entire range of colors a device can produce. As shown in the diagram above, the digital gamut (sRGB) is significantly larger than the physical paint gamut.

When our software analyzes your custom photo, it has to perform a "gamut mapping." It takes those super-bright neon colors from your screen that do not exist in the paint world and maps them to the closest available paint color. This inevitably results in a loss of saturation and "glow."

This is why photos of sunsets, neon signs, or brightly lit flowers often look more subdued on canvas. The paint is accurate; it is simply limited by physics.

3. How to Choose a Photo for Success

Understanding this limitation allows you to choose photos that translate beautifully into paint. To get the best results from your Custom Kit, follow these guidelines:

• Avoid "Neon" lighting: Photos with intense, glowing light sources (like the example in our header image) will always look duller in paint.
• Focus on Contrast, not just Color: A photo with strong highlights and deep shadows will translate better than a flat photo with bright colors. Paint excels at showing form through value changes.
• Ensure High Resolution: Our software needs clear details to create accurate numbered zones. A blurry photo will result in a blurry painting.

Once you have your kit, remember that the final presentation matters. Ensure your canvas is perfectly flat and taut by using our DIY Wooden Frame Kit. A stretched canvas reflects light more evenly, maximizing the vibrancy of the pigments you do have.

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About the Author

William Murdock is the Founder of Paint On Numbers. He specializes in the technical application of acrylic mediums and helps hobbyists bridge the gap between DIY kits and professional archival standards.