What is a Cyanotype (Sunprint)?
The Cyanotype is one of the oldest photographic printing processes in history, invented in 1842 by Sir John Herschel. Unlike modern photography which uses silver, the cyanotype process relies on a mixture of iron compounds.
When a piece of paper coated in these chemicals is exposed to ultraviolet light (like the sun) and then washed in water, it produces a stunning, permanent, monochromatic image in vibrant Prussian Blue. Historically, this process was used by botanist Anna Atkins to record plant silhouettes (creating the first “Sunprints”) and by engineers to quickly reproduce architectural drawings (which is where the term “Blueprint” comes from).
🟦 Cyanotype & Sunprint Engine
Simulate the historic 19th-century Prussian Blue photographic printing process. Turn digital photos and sketches into authentic architectural blueprints and organic sunprints.
Recreating Historic Chemistry Digitally
Creating a realistic cyanotype digitally is incredibly difficult. If you simply place a blue color filter over a digital photo, the result looks flat and fake.
The Image Cyanotype Engine bypasses standard color filters and uses a mathematical Tri-Tone Luminance Mapper. It reads the physical light values of your digital photo and maps them to a specific chemical color scale: crushing the deep shadows into rich navy blue, coloring the midtones a vivid cyan, and leaving the bright highlights as pale paper-white.
How to Process Your Digital Sunprint
- Upload Your Photo: Drag and drop your image. Photos with high contrast and distinct silhouettes (like portraits, trees, or architecture) produce the most authentic sunprint results.
- Select Your Exposure Style:
- Standard Sunprint: This creates a standard “Positive” image. Shadows remain dark blue, and light skies remain pale.
- Blueprint Mode: If you upload a dark pencil sketch or line-art drawing, select Blueprint Mode. This mathematically inverts the light values of your image before applying the blue chemistry, turning dark lines into white lines on a rich blue background—creating a perfect architectural blueprint.
- Adjust the Sun Exposure: In real-world printing, leaving the paper in the sun for too long creates a darker, heavier blue image. Use the Exposure Time slider to darken or lighten your digital print.
- Add Paper Fiber Texture: Real cyanotypes are painted onto thick, textured watercolor paper. Increase the Paper Texture slider to generate a procedural fiber overlay that gives your digital image a physical, analog feel.
Frequently Asked Questions
Are my personal photos uploaded to a server?
No. This tool is built using a secure, client-side HTML5 Canvas processing loop. All of the luminance mapping and pixel coloring happens entirely inside your web browser. Your files never leave your computer, ensuring absolute privacy.
Why does the image resize when I upload a massive file?
Applying a pixel-by-pixel mathematical color map and procedural paper noise to massive smartphone images can freeze web browsers. To ensure the tool stays instantly responsive while you adjust the exposure sliders, the engine safely caps internal processing at 2400 pixels on the longest edge, which is still ultra-high resolution for web and print.