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Synthetic Test Images for GRIME AI and NAU Phenocam GCC Benchmark Comparison


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Created: Nov 26, 2025 at 4:30 p.m. (UTC)
Last updated: May 28, 2026 at 3:23 p.m. (UTC) (Metadata update)
Published date: May 28, 2026 at 3:23 p.m. (UTC)
DOI: 10.4211/hs.f00ccf6584c042e59d36bf66bd5a2480
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Abstract

Validation evidence for green chromatic coordinate (GCC) calculations produced by GRIME AI (GaugeCam Remote Image Manager Educational Artificial Intelligence). Synthetic test images with known color properties were generated using a Python script producing two image types used in the GCC comparison: solid-color images with uniform fill (flat) and solid-color images with a stipple effect applied via Gaussian-blurred random noise (stippled). Both types span 65 green hues across an 8 x 8 grid of HSV saturation and value levels plus one pure green [0, 255, 0] image, at a resolution of 1024 x 768 pixels saved as JPEG. The script additionally produces splotch images — circular green patches composited onto a clay-colored background in flat and stippled permutations — which are included in the deposit but were not used in the GCC comparison analyses. GCC values were independently computed by GRIME AI and by the PhenoCam Network pipeline (Northern Arizona University) and manually compiled into a spreadsheet for comparison.

GCC values computed by GRIME AI were compared against GCC values computed by the PhenoCam Network pipeline, used here as a benchmark reference, across both flat and stippled solid image sets. Agreement between the two implementations was near-perfect: flat images yielded a mean absolute difference of 0.0% (SD = 0.00003) and stippled images yielded a mean absolute difference of 0.0% (SD = 0.0002). These statistically insignificant discrepancies are attributed to minor floating-point rounding differences introduced by CPU architecture variation during image processing rather than any methodological inconsistency, confirming that GRIME AI produces reproducible and accurate greenness calculations consistent with an established community standard.

A secondary analysis examined the effect of image serialization on GCC consistency by comparing GRIME AI calculations performed on images held in memory against calculations performed on those same images after saving to disk and reloading. Results were evaluated separately for flat images (mean difference = 0.02%, SD = 0.00383) and stippled images (mean difference = 0.03%, SD = 0.00344). Both differences are traced to JPEG lossy compression, which introduces small per-channel rounding errors at the pixel level (e.g., a pure green pixel [0, 255, 0] becomes [0, 255, 1] after a save-reload cycle). The slightly larger variability in stippled images is consistent with greater spatial heterogeneity providing more opportunity for compression artifacts to accumulate. The dataset includes the image generation script, all synthetic test images, and a spreadsheet recording GCC outputs from both GRIME AI and PhenoCam alongside computed differences.

Subject Keywords

Content

README.md

GRIME AI GCC Validation Against PhenoCam

Overview

This dataset provides validation evidence for green chromatic coordinate (GCC) calculations produced by GRIME AI (GaugeCam Remote Image Manager Educational Artificial Intelligence). Two comparison analyses are included: (1) cross-platform agreement between GRIME AI and the PhenoCam Network pipeline (Northern Arizona University, benchmark reference), and (2) within-platform consistency between GCC computed on in-memory images versus those same images after saving to disk and reloading as JPEG. GCC outputs from each platform were manually compiled into a spreadsheet for comparison.

Contents

``` Software - Generate Test Images/ create_greenness_test_images.py Image generation script create.bat Windows batch launcher requirements.txt Python dependencies test_images/ masks/ 4 mask images (white/black, RGB/grayscale) in JPG, PNG, and TIF solids/ flat/ 65 solid flat-fill green JPEGs + 20250718_1200_Solid_Flat_Images_Info.xlsx textured/ 65 solid stippled green JPEGs + 20250718_1500_Solid_Textured_Images_Info.xlsx splotches/ flat_flat/ 32 JPEGs: flat clay background, flat green splotches + Splotch_flat_flat_Images.xlsx flat_textured/ 32 JPEGs: flat clay background, stippled green splotches + Splotch_flat_textured_Images.xlsx textured_flat/ 32 JPEGs: stippled clay background, flat green splotches + Splotch_textured_flat_Images.xlsx textured_textured/ 32 JPEGs: stippled clay background, stippled green splotches + Splotch_textured_textured_Images.xlsx Test Files Sent or Uploaded to NAU on 2025_07_18/ Flat and stippled solid JPEGs + metadata XLSXs submitted to NAU PhenoCam for GCC computation

Test Results & Analysis/ GCC - Test Results - Memory Image vs. File Image (JPG) Differences.xlsx GCC outputs from GRIME AI (memory and file) and PhenoCam (file) with computed differences ```

Synthetic Image Design

All images are 1024 x 768 pixels, saved as JPEG at quality=100. Images were generated on 2025-07-18 using create_greenness_test_images.py.

Solid flat images — 65 images. Colors span an 8 x 8 grid of HSV saturation (0.2–1.0) and value (0.2–1.0) at a fixed green hue (100°), plus one pure green [0, 255, 0] image. Each image is a uniform fill of a single color. These images were used in the GCC comparison analyses.

Solid stippled images — 65 images. Same color grid as the flat set. Each image applies Gaussian-blurred random noise (amplitude ±20 DN) to the base color, producing a stipple texture. These images were used in the GCC comparison analyses.

Splotch images — 32 images per permutation (4 permutations), not used in the GCC comparison analyses. Each image composites 50 circular green splotches of randomized radius (20–100 px), saturation (0.2–1.0), and value (0.2–1.0) onto a clay-colored background (RGB: 160, 82, 45). Background and splotch patches are independently flat or stippled across the four permutations.

Mask images — 4 images covering all combinations of fill color (white, black) and channel depth (1-channel grayscale, 3-channel RGB), each saved in JPG, PNG, and TIF formats.

Workflow

The solid flat and solid stippled images were submitted to the PhenoCam Network (NAU) for independent GCC computation. The files submitted are preserved in Test Files Sent or Uploaded to NAU on 2025_07_18/. GCC values returned by PhenoCam and computed independently by GRIME AI were manually entered into the comparison spreadsheet.

Validation Results Summary

Analysis Image Type Mean Difference SD
GRIME AI vs. PhenoCam Flat 0.0% 0.00003
GRIME AI vs. PhenoCam Stippled 0.0% 0.0002
Memory vs. file (JPEG round-trip) Flat 0.02% 0.00383
Memory vs. file (JPEG round-trip) Stippled 0.03% 0.00344

Cross-platform differences are attributed to floating-point rounding variation across CPU architectures. Memory-vs-file differences are attributed to JPEG lossy compression (e.g., [0, 255, 0] → [0, 255, 1] after a save-reload cycle).

Reproducing the Test Images

bash pip install -r requirements.txt python create_greenness_test_images.py

Output is written to test_images/ with subdirectories for solids, splotches, and masks.

Software

GRIME AI source code: https://github.com/JohnStranzl/GRIME-AI

Citation

Stranzl Jr., J. E. (2026). GRIME AI GCC Validation Against PhenoCam, HydroShare. [DOI pending]

License

Creative Commons Attribution CC BY 4.0 — http://creativecommons.org/licenses/by/4.0/

Code is licensed under the Apache License 2.0.

Funding

This work was supported by the U.S. National Science Foundation under Award No. 2411065 — Innovative Resources: Cyberinfrastructure and community to leverage ground-based imagery in ecohydrological studies.

Related Resources

This resource is described by https://github.com/JohnStranzl/GRIME-AI

Credits

Funding Agencies

This resource was created using funding from the following sources:
Agency Name Award Title Award Number
U.S. National Science Foundation Innovative Resources: Cyberinfrastructure and community to leverage ground-based imagery in ecohydrological studies 2411065

How to Cite

Stranzl Jr., J. E. (2026). Synthetic Test Images for GRIME AI and NAU Phenocam GCC Benchmark Comparison, HydroShare, https://doi.org/10.4211/hs.f00ccf6584c042e59d36bf66bd5a2480

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

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