The Technical Guide to Custom Paint by Numbers: Resolution, Ratios & Lighting
Summary
Ordering a custom paint by numbers kit is an investment in a memory. Don't let a bad photo ruin the result. This technical guide explains the mathematics of resolution (PPI), the physics of lighting (dynamic range), and the geometry of aspect ratios to ensure your custom kit is flawless.
The old saying "garbage in, garbage out" is the golden rule of custom manufacturing. We use the finest linen canvases and heavy-body acrylics, but we cannot magically add detail to a blurry photo.
Before you upload your cherished memory to create a standard Custom Paint by Numbers Kit, you need to understand the technical requirements that make a photo "paintable."
Figure 1: A high-resolution source photo is the prerequisite for a detailed final painting.
1. The Mathematics of Resolution (Pixels Per Inch)
Just because a photo looks good on a 6-inch phone screen does not mean it will look good blown up to a 50cm canvas. This is a matter of PPI (Pixels Per Inch).
For a sharp canvas print, we generally need the source image to provide roughly 150-200 PPI at the final output size. If you upload a tiny photo downloaded from Facebook, the software has to "guess" the missing data, resulting in a blocky, blurry mess.
Figure 2: The Resolution Matrix. Use original camera files, not social media screenshots, for larger canvases.
2. The Aspect Ratio Trap
Mathematics is stubborn. You cannot fit a square peg into a round hole, and you cannot fit a square Instagram photo onto a rectangular canvas without consequences.
This is called the Aspect Ratio. If you select a 40x50cm canvas (a 4:5 ratio) but upload a square photo (1:1 ratio), our designers have two choices: stretch the image (which looks awful) or crop it. Bad cropping ruins compositions.
Figure 3: Ensure your subject is centered so essential details (like ears!) aren't cropped off by the canvas shape.
Aspect ratio and lighting are critical when ordering our specialised Custom Pet Paint by Numbers kits.
If you have a black dog or a white cat, do not use flash. Flash flattens fur texture into a solid blob of colour. Use natural, sideways daylight to create shadows that define individual strands of fur. If the camera can't see the fur texture, the paint won't show it either.
3. Lighting Physics: Dynamic Range
The human eye is amazing; it can see details in bright highlights and dark shadows simultaneously. Cameras are not that good.
If your photo has harsh backlighting (the sun behind the subject), the subject will be a dark silhouette. If the photo is taken at night, it will have "digital noise" (grain). A paint by numbers algorithm interprets this noise as confetti, creating a messy final image with random specks of colour.
- The Golden Rule: Always use even, natural daylight. Avoid harsh noon sun and dark indoor lighting.
4. Colour Gamut: Screen vs. Pigment
Finally, manage your expectations regarding colour. Your phone screen uses light (RGB) to create neon, highly saturated colours. Physical acrylic paint uses pigment (CMYK/Pantone).
Very bright, fluorescent colours on a screen will always look slightly more muted in real life. Our designers manually optimize colours to get the closest possible match to realistic pigment shades.
Got the Perfect Photo?
Now that you understand the science, turn that memory into a masterpiece.
Upload Your Photo (Standard) Upload Your Pet Photo
Common Questions About Custom Kit Photos
What is the minimum resolution for a custom paint by numbers?
For a standard 40x50cm canvas, we recommend a file size of at least 2MB or a resolution of roughly 2000 pixels on the shortest side. This ensures roughly 150 PPI (pixels per inch) for a sharp print.
Can I use a screenshot from Facebook or Instagram?
No. Social media platforms compress images, removing nearly 60% of the data. While they look fine on a phone screen, they will appear pixelated and blocky when blown up to canvas size.
Why are heads or ears sometimes cropped off in the preview?
This is an Aspect Ratio issue. If you upload a square photo (1:1) for a rectangular canvas (4:5), the image must be cropped to fit. Always try to choose a canvas shape that matches your photo's shape.
How do I avoid "black blobs" in my custom painting?
Black blobs are caused by shadows. If a photo is backlit or taken in low light, the camera records the dark areas as pure black. The paint by numbers software translates this into large, detail-less shapes. Always use photos taken in even, bright daylight.