Undertone is a color analysis application for painters, photographers, and designers. It analyzes images captured with the device camera or imported from a photo library, and presents the color structure of each image across four layers: palette with proportions, color harmony, temperature map, and value structure. Common use cases include mixing paint, color grading photographs, and designing with color. The app is intended for users who need to understand color relationships rather than simply select individual colors. The palette layer displays dominant colors in order of visual weight, with swatch sizes proportional to the area each color occupies in the image. Each swatch is labeled with a hex value and a painter-friendly color name. The harmony layer plots detected colors on a color wheel and identifies the closest geometric match among standard harmony types, including complementary, analogous, triadic, split-complementary, tetradic, square, and monochromatic. The temperature map provides a visual overlay that distinguishes warm and cool regions in the image. The value structure layer converts the image to grayscale and separates it into light, mid-tone, and dark zones. A typical workflow involves pointing the camera at a subject or importing an existing image, with full analysis completed in under five seconds. Every analysis is saved automatically, allowing the app to serve as a local color reference library. All analysis is performed on the device, and user images are never sent to external servers. Analysis history is stored locally. No account, sign-up, or email is required. The app collects only anonymous usage statistics and crash reports, tied to a random identifier, to support software improvement. Undertone is available as a one-time purchase with no subscription.