quadGEN

Overview

Global corrections can be applied in two ways: directly via a curve/LUT file, or by computing a linearization from L* measurements. Both approaches update all channels uniformly.

Working Assumptions

• Positive space: X=0% is white → X=100% is black; Y=0% = no ink (white), Y=100% = max ink (black).
• Endpoints anchored: Keep 0→0 and 100→100 fixed unless you have a specific reason to change them.
• Monotonic, smooth curves: Avoid kinks or flat spots, especially near endpoints.
• Digital negatives: Work in positive space; invert your image in the editor when making a digital negative.

Applies Directly →

• Photoshop Curves (.acv): Curve presets.
• LUT (.cube): 1D or 3D LUT.

Calculates Linearization ↕

• LAB Data (.txt): L* measurements.
• Manual L* Entry: L* measurements.

Tonal Zones

• Highlights: 0–25% (X)
• Midtones: 25–75% (X)
• Shadows: 75–100% (X)

Workflow Summary

1. Choose your printer and set ink limits for each channel.
2. Export a test .quad and print a 0–100% step wedge.
3. Measure the positive result (inkjet print or alt‑process print).
4. Load data into quadGEN: LAB (.txt), EDN LUT (.cube/.acv), or Manual L*.
5. Review the graph and adjust channel limits if needed.
6. Export the corrected .quad and reprint to verify.

Auto endpoint rolloff

Temporarily disabled while we retune the shoulder/toe detector. Existing projects keep previously baked knees, but quadGEN will not generate new auto rolloff adjustments until the retune ships.

Sample Data