Duotone Gradient Map
Duotone Gradient Map: Calculates Rec. 601 luminance for each pixel and maps it between the selected shadow and highlight colors by linear interpolation. Processing stays in your browser.
About this duotone gradient map
Map each pixel's Rec. 601 luminance between selected shadow and highlight colors using linear interpolation.
How this tool works
Implements client-side Duotone Gradient Map operations. Calculates Rec. 601 luminance for each pixel, then maps shadows and highlights between the two user-selected sRGB colors by linear interpolation. Alpha is retained.
- Binary Segment & EXIF Header Parsing: Identifies JPEG APP1 or PNG chunks, extracting and reporting embedded GPS coordinates and camera metadata.
- EXIF Scrubbing Pipeline: Reconstructs clean binary streams omitting metadata segments without lossy re-encoding.
- Convolution & Pixelation Matrix: Applies 2D spatial convolution matrices (Gaussian blur, box blur, sharpen) or regional pixelation blocks.
- QR Matrix Synthesis: Encodes text or URLs into ISO/IEC 18004 QR code matrix with Reed-Solomon error correction (L, M, Q, H).
Worked example
Scenario: Map a decodable 12×9 test PNG between the default two colors.
Sample input:
Processing: Canvas maps each pixel with Rec.601 luma and linear RGB interpolation.
Illustrative output:
Limits and verification
Scrubbing EXIF metadata is completely lossless because compressed image bitstreams are not re-encoded. Privacy blur and pixelation are destructive pixel operations that permanently overwrite original image data (preventing de-blurring recovery).
Examples demonstrate an expected workflow; they do not prove every input or every branch of an external specification. Check important results with an independent source before using them for money, security, compliance, safety, or irreversible file changes.
Browser processing boundary
Tool input is processed by code running in the browser and is not intentionally sent to a CZOA processing API. The page can still request ordinary site assets, analytics, or advertising when those services are enabled. Browser extensions and managed-device software remain outside this tool's control.
Relevant references
These references govern or help explain the format, protocol, or calculation used here. Listing a reference does not claim certification or complete implementation of every optional feature.
Content owner: CZOA Tools · Last reviewed: 2026-09-15 · Review methodology
How to use it
- Enter, paste, or select your input data into the Duotone Gradient Map workspace controls.
- Review available parameter fields, units, formats, or options configured for your task.
- Click the action button or observe immediate live calculations rendered in your browser runtime.
- Inspect the resulting output and any diagnostic messages, then copy or download the result if needed.
Frequently asked questions
How does Duotone Gradient Map process image pixels?+
After drawing the decoded image, it reads Canvas ImageData and maps each pixel with Rec.601 weight (.299 R + .587 G + .114 B) / 255 between the chosen shadow and highlight RGB colors. Alpha is retained and the result is exported as a PNG data URL.
What controls does Duotone Gradient Map provide?+
The page has one image-file chooser, Shadow color and Highlight color pickers, and Process locally. Defaults are #172554 and #fbbf24. It has no gradient stops, blend mode, curve, color space, dithering, alpha, format, preset, or batch control.
What limits apply to duotone mapping?+
The image must decode in the browser. The mapping uses the stated Rec.601 coefficients and simple linear RGB interpolation, not perceptual color management, ICC profiles, arbitrary gradients, selective masks, or reversible preservation of the source colors.
What does browser-isolation evidence establish for duotone mapping?+
Network requests observed during the example contained no selected-image payload while the fixture produced and independently decoded a PNG whose sampled pixel matched the independent Rec.601 interpolation for the default shadow and highlight colors. This supports only the tested browser value path; resources, extensions, permissions, and other networks are outside the observation.