Optimizing Image Preparation and Compression for Face Recognition within 1024 Bytes
Pith reviewed 2026-06-30 06:39 UTC · model grok-4.3
The pith
JPEG AI compression preserves face recognition accuracy best when fitting images into 1024 bytes.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The recently standardised JPEG AI, when using optimized settings, provides the best face recognition performance for facial images compressed to a maximum of 1024 bytes, in particular when the comparison includes only images with high face image quality. AVIF and WebP also provide good results. The losses caused by the strong lossy compression are comparatively small. For the comparison of ICAO-compliant face images only, converting the images to grayscale proves to be a helpful preprocessing step, whereas for comparisons involving less suitable samples, preserving color is preferable. In addition, smoothing and resizing the images beforehand also turns out to be beneficial.
What carries the argument
Optimization of preprocessing steps and compression configurations across multiple codecs to reach the 1024-byte target while minimizing impact on face recognition match scores.
Load-bearing premise
The face recognition performance measured on the chosen test images and algorithms will generalize to the range of real-world face images encountered in travel document applications.
What would settle it
Re-running the same compression and preprocessing pipeline on a new dataset of travel-document-style images captured under varied lighting and poses, using a different face recognition algorithm, would show whether JPEG AI retains its performance lead.
Figures
read the original abstract
ICAO-compliant machine readable travel documents enable automated biometric face verification. The biometric reference is stored on an RFID chip included in form of a JPEG or JPEG 2000 compressed facial image. In contrast, temporary travel documents lack of machine readability, which excludes the owner from such automated processes. This disadvantage could be solved by equipping such documents with 2D barcodes. This technology offers a resource-saving alternative to expensive RFID chips, while still offering machine readability and fast issuing processes. However, this solution introduces the challenge of storing the face images at significantly smaller storage capacities, creating the need for reducing the file size of the included facial image to a maximum of 1024 bytes. This study examines preprocessing steps and compression configurations, using JPEG, JPEG 2000, JPEG XL, JPEG AI, HEIF, AVIF, and WebP for image compression to this target size, while still preserving as much face recognition performance as possible. While the reference sample must always comply with ICAO specifications, the individual samples may or may not meet these requirements, depending on the application. This work optimizes compression steps for both of these prerequisites. It is shown that the recently standardised JPEG AI, when using optimized settings, provides the best face recognition performance, in particular when the comparison includes only images with high face image quality. AVIF and WebP also provide good results. The losses caused by the strong lossy compression are comparatively small. For the comparison of ICAO-compliant face images only, converting the images to grayscale proves to be a helpful preprocessing step, whereas for comparisons involving less suitable samples, preserving color is preferable. In addition, smoothing and resizing the images beforehand also turns out to be beneficial.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript investigates preprocessing and compression techniques to store ICAO face images at a maximum of 1024 bytes for 2D barcodes on temporary travel documents, comparing JPEG, JPEG 2000, JPEG XL, JPEG AI, HEIF, AVIF, and WebP. It reports that JPEG AI with optimized settings yields the highest face recognition performance, especially when restricting comparisons to high-quality images, with AVIF and WebP also competitive; grayscale conversion aids ICAO-compliant samples while color preservation helps lower-quality ones, and smoothing/resizing is generally beneficial. The work addresses both strictly compliant and mixed-quality regimes.
Significance. If the empirical rankings hold under broader conditions, the results could enable machine-readable temporary travel documents without RFID hardware, supporting automated biometric verification in resource-constrained settings. The codec comparison across two quality regimes supplies concrete implementation guidance for the 1024-byte constraint.
major comments (3)
- [Results] Results section: the abstract and main findings assert JPEG AI superiority based on comparative face recognition performance, yet the manuscript provides no description of the datasets, exact metrics (e.g., verification rates at fixed FAR), error bars, statistical tests, or exclusion criteria for 'high face image quality' samples. This prevents verification of the central claim.
- [Experimental setup / Discussion] Experimental setup and discussion: no evidence is given that the test images span the relevant axes of real-world ICAO travel-document variability (demographics, pose, illumination, sensor noise, document degradation). The reported codec ranking therefore rests on an untested generalization assumption flagged in the abstract.
- [Methods] Methods: the optimization of codec-specific parameters is described only at a high level; without the exact parameter sets, preprocessing pipelines, or face recognition back-ends used, the 'optimized settings' result cannot be reproduced or stress-tested.
minor comments (1)
- [Abstract] Abstract: the specific face recognition performance metric (e.g., TAR at 0.01 FAR) and the number of images per regime should be stated explicitly rather than left as 'best performance.'
Simulated Author's Rebuttal
We thank the referee for the constructive and detailed comments. We address each major point below and indicate the revisions that will be incorporated to improve clarity, reproducibility, and transparency.
read point-by-point responses
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Referee: [Results] Results section: the abstract and main findings assert JPEG AI superiority based on comparative face recognition performance, yet the manuscript provides no description of the datasets, exact metrics (e.g., verification rates at fixed FAR), error bars, statistical tests, or exclusion criteria for 'high face image quality' samples. This prevents verification of the central claim.
Authors: We agree that the manuscript would benefit from greater detail on these elements to allow independent verification. In the revised version we will add a dedicated experimental setup subsection describing the datasets, the exact metrics (including verification rates at fixed FAR), error bars, statistical tests performed, and the precise quality-assessment criteria used to select high-quality samples. revision: yes
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Referee: [Experimental setup / Discussion] Experimental setup and discussion: no evidence is given that the test images span the relevant axes of real-world ICAO travel-document variability (demographics, pose, illumination, sensor noise, document degradation). The reported codec ranking therefore rests on an untested generalization assumption flagged in the abstract.
Authors: The datasets are drawn from established face-recognition benchmarks that include demographic, pose, and illumination variation. We will expand the Experimental Setup and Discussion sections to explicitly relate these characteristics to ICAO requirements, acknowledge the limits of the tested conditions, and more prominently flag the generalization assumption. Additional real-world ICAO-specific degradation data would strengthen the claims but is outside the present scope. revision: partial
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Referee: [Methods] Methods: the optimization of codec-specific parameters is described only at a high level; without the exact parameter sets, preprocessing pipelines, or face recognition back-ends used, the 'optimized settings' result cannot be reproduced or stress-tested.
Authors: We concur that full reproducibility requires the concrete parameter values. The revised manuscript will include the exact codec parameter sets, the complete preprocessing pipelines (smoothing kernels, resizing factors, color/grayscale decisions), and the face-recognition back-end models and implementations, placed either in the main text or as supplementary material. revision: yes
Circularity Check
No circularity: purely empirical evaluation of codecs and preprocessing
full rationale
The paper reports experimental results from testing JPEG-family codecs and preprocessing steps (grayscale, smoothing, resizing) on face recognition accuracy at a 1024-byte target. No equations, fitted parameters, or derivations are present; performance rankings are measured directly on chosen test sets rather than predicted from any model whose inputs include the target metric. No self-citation chains or uniqueness theorems are invoked to support the central claims. The work is therefore self-contained against external benchmarks and receives the default non-circularity finding.
Axiom & Free-Parameter Ledger
free parameters (1)
- codec-specific compression parameters
Reference graph
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discussion (0)
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