JacksBlog

Extract ICC Files Directly from Most Image Files

Thu, 26 Feb 2026 20:00:00 +0800

A simple, universal method based on ICC file structure features, without relying on specific image formats

HDR Image Formats (VI): Decoding and Conversion of iPhone HEIC Photos

Thu, 19 Feb 2026 23:00:00 +0800

Analysing HDR images in iPhone photos in HEIC format to understand their structure, decoding, and conversion process.

What Happens When You Get the Baseline Headroom Wrong

Sun, 01 Feb 2026 23:50:00 +0800

Baseline Headroom in ISO 21496-1: A Bug and Some Curious Findings

Hisense’s Four-Primary TV: Colour Gamut and Visiual Health

Sat, 10 Jan 2026 00:00:00 +0000

How the added cyan LED affects gamut coverage and its potential impact on human circadian rhythm

Bit Packing in DNG Images and Its Implementation

Sat, 03 Jan 2026 00:33:13 +0800

Efficiently pack 10/12/14-bit RAW data for DNG using Numpy. Learn to handle padding for odd widths and discover numpy2dng, a bug-fixed alternative to PiDNG.

HDR Image Formats (V): Understanding Headroom in Gainmap

Wed, 17 Dec 2025 23:08:09 +0800

Through a case study, understand a seemingly redundant parameter when encoding HDR images: the role of Alternate HDR Headroom in the ISO 21496-1 standard

Assembling DNG To Get Day0 Support For New Cameras

Sun, 07 Dec 2025 18:30:00 +0800

Use LibRAW to break down RAW components, then manually piece together a usable DNG file with PiDNG.

A First Look at Mobile Phone Log: OPPO Log as an Example

Tue, 25 Nov 2025 01:00:00 +0800

Are Log video on Android a professional tool or just marketing? The technical details of OPPO Log curve and examines its performance through two examples.

The Artistic Journey of a Green Bean: DIY Coffee Roasting

Sun, 16 Nov 2025 23:00:00 +0800

Pros and cons of home roasting: Matchbox H7S Lite Experience

A New Python AVIF Encoding Option: ImageCodecs

Mon, 10 Nov 2025 23:00:00 +0800

Encode high bit-depth NumPy arrays directly to AVIF in Python using ImageCodecs and libavif, with HDR, lossless, and quality/speed options.

Geekon Monitor Unboxing: High-end Aspiration, Workshop Reality

Thu, 23 Oct 2025 23:00:00 +0800

High specs, high price, and high-end looks, but not quite high-end. This Geekon monitor boasts a 6K panel, 92% BT.2020 color gamut, and 20 luminance.

Solving WSL Installation Failure Caused by Invisible Hyper-V

Wed, 15 Oct 2025 23:29:04 +0800

Enable hidden Hyper-V with DISM to fix WSL2 install errors. Run AI tools like Codex in Unix CLI for precise edits using sed, awk, diff, and patch.

Decoding an Adaptive HDR Tone Mapping Method (Wang, 2025)

Tue, 23 Sep 2025 00:30:00 +0800

Adaptive HDR-to-SDR tone mapping for 0-1000 nits HDR to SDR. Uses max RGB luminance, tone compression, detail and dark enhancement. Wang et al. (2025).

My Zotero: Configuration and Core Plugins

Sun, 14 Sep 2025 00:00:00 +0800

Streamline your Zotero setup with plugins for metadata retrieval, PDF automation, and translation tools—improve accuracy and efficiency in research workflows.

Good Night, Azukisan

Tue, 09 Sep 2025 22:00:00 +0800

MacAdam's Optimal Colours: The Boundary of Physical Colours

Sun, 07 Sep 2025 20:00:00 +0800

Explore Schrödinger's theory on the limit of object colors and optimal pigment calculations.

HDR Image Formats (IV): ISO 21496-1 the Unified Gainmap

Sat, 30 Aug 2025 03:00:00 +0800

ISO 21496-1 standardizes Gainmap metadata, defining HDR imaging with a universal JPEG APP2 format, unifying previously proprietary formats like UltraHDR.

A Quick Analysis of the X2D II 100C File Format

Tue, 26 Aug 2025 23:00:00 +0800

Hasselblad HNCS HDR outputs Ultra HDR JPEG with Gainmap and P3 color via Phocus, the first medium format camera with end-to-end HDR.

HDR Image Formats (III): UltraHDR and MPF

Tue, 26 Aug 2025 01:00:00 +0800

Identify UltraHDR images by detecting hdrgm:Version=1.0 in the JPEG's metadata, per Google's spec, which includes a primary image and gainmap for HDR rendering.

HDR Image Formats (II): JPEG and Its Modifications

Sun, 24 Aug 2025 02:00:00 +0800

Learn JPEG file structure: SOI/EOI markers, metadata, JFIF format. Use a free parser to analyze binary segments (FF D8, FF D9) and compressed data.

Using LLMs for Colour Science: Best Practices and Test

Thu, 21 Aug 2025 02:00:00 +0800

Use LLMs for technical tasks: avoid direct math, leverage Chain-of-Thought, handle long contexts.

Decoding HDR Image Formats (I): Basic Concepts of Gainmap

Tue, 19 Aug 2025 00:00:00 +0800

Gainmaps and UltraHDR enhance JPEGs with dual-layer HDR, using a base image and a gainmap with XMP metadata like Min, Max, and Gamma.

CAT16: Why Are Two Steps Needed to Ensure Reversibility?

Thu, 07 Aug 2025 18:00:00 +0800

CAT16 model: two-step chromatic adaptation ensures reversibility, unlike one-step methods.

📷 July Collection

Tue, 05 Aug 2025 00:00:00 +0800

(25 Images) Sunsets, Fiery Clouds, Rainbows, and Cats

Add a Little Gadget, and Talk About How I Update Articles

Mon, 04 Aug 2025 02:00:00 +0800

Hugo blog automation: GitHub Actions deployment, draft management, LLM post-processing for multilingual content.

Objective Test Procedures for Sony Camera Displays

Fri, 01 Aug 2025 12:00:00 +0800

Learn how to transfer metadata using Exiftool and Pillow to display test images on Sony camera screens for display colorimetry analysis and gamut measurement.

How to Completely Remove a File from Git History

Sun, 29 Jun 2025 01:03:00 +0800

Use git-filter-repo to remove large or sensitive files from Git history. Rewriting changes commit hashes—backup and alert collaborators first.

📷 Cats in a Mate Tea Shop

Sat, 28 Jun 2025 18:00:00 +0800

(9 Images) Some cat energy

Instructions and Test Page

Fri, 20 Jun 2025 00:00:00 +0800

Click five times on the version number to enter developer mode

Principles of Colour Reproduction in Digital Images Notes: Colour Reproduction and Gamut

Wed, 04 Jun 2025 23:30:00 +0800

Learn color reproduction goals: spectral, colorimetric, perceptual rendering, gamut mapping, intents, and viewing conditions.

An Experiment to Understand HDR Transfer Functions

Mon, 26 May 2025 02:00:00 +0800

Learn BT.2408 HDR transfer functions, PQ, and HLG with Python—fix 18% grey card luminance issues and master accurate HDR workflows.

iCAM06: Colour Appearance Model in Image Processing

Tue, 13 May 2025 20:00:00 +0800

iCAM06: HDR rendering with color models & tone compression for accurate display reproduction.

HDR Image Format Conversion

Fri, 25 Apr 2025 00:00:00 +0800

Digital images are pixel arrays compressed by JPG with DCT and Huffman coding, accurately displayed via color spaces and formats like TIFF.

Not Just Colour Difference: Evaluate Image with Colour Chart

Wed, 02 Apr 2025 13:30:00 +0800

Dive into color analysis: sRGB to CIELAB, DeltaE2000, ISP effects, AE influence, and accuracy in final JPG output. Understand the full imaging pipeline.

How to Correctly Read RAW Files

Fri, 28 Mar 2025 00:00:00 +0800

Compare dcraw, Rawpy, and LibRaw for extracting RAW image data. Analyze their support for Sony, Canon, Hasselblad, Fujifilm cameras and 16-bit TIFF demosaicing.

Reflectance: Another Path to Readability in Bright Environments

Fri, 14 Mar 2025 16:00:00 +0800

Analyzes the mobile display brightness race, explaining why high-nit specs offer limited practical value and comparing solutions for outdoor readability.

Reincarnated into the ISP Isekai Day 0: Lost in the RAW Forest, I Summon RGB with a 3x3 Magic Array

Tue, 04 Mar 2025 00:00:00 +0800

Forge your own ISP from RAW to sRGB using color science, CCM, and gamut mapping—craft a custom processor like a true pixel engineer.

Colour Space Conversion: RAW to XYZ

Sun, 02 Mar 2025 00:00:00 +0800

how camera RAW RGB converts to XYZ using CCM, spectral sensitivity, colour matching functions, and tristimulus calculations in colour science.

Colour Space Conversion: RGB to XYZ

Sun, 23 Feb 2025 00:00:00 +0800

Build a precise RGB to XYZ matrix using sRGB primaries, white point (0.3127, 0.3290), and the non-linear transfer function for accurate color conversion.

Principles of Colour Reproduction in Digital Images Notes: Colour Measurement

Fri, 21 Feb 2025 00:00:00 +0800

Explore color measurement: spectral separation for flexibility, integration for direct tristimulus values. Compare spectrophotometers vs. imaging photometers.

Principles of Colour Reproduction in Digital Images Notes: Colour Appearance

Fri, 07 Feb 2025 00:00:00 +0800

CIECAM16 predicts colour appearance across viewing conditions for cross-media reproduction, considering background, light source, and adaptation.

Principles of Colour Reproduction in Digital Images Notes: Chromatic Adaptation Transform

Mon, 03 Feb 2025 00:00:00 +0800

Learn chromatic adaptation models (CAT02, CAT16, von Kries) for color constancy—stable color perception under varying lighting in visual science.

Principles of Colour Reproduction in Digital Images Notes: Illuminants and Light Sources

Sat, 01 Feb 2025 00:00:00 +0800

Explore black-body radiation theory: ideal thermal emitter properties, Planck's law formula, color temperature, and spectral radiant exitance calculations.

Principles of Colour Reproduction in Digital Images Notes: Fundamentals of Colorimetry

Sat, 25 Jan 2025 00:00:00 +0800

Explore quantitative colorimetry: color mixing, CIE systems, CIELAB, CIEDE2000, and Munsell Colour System for color measurement.

Principles of Colour Reproduction in Digital Images Notes: Light and Vision

Tue, 21 Jan 2025 00:00:00 +0800

Explore light properties, human eye response, and how the CIE function converts radiometric to photometric units like lumens and lux.

Principles of Colour Reproduction in Digital Images Notes: Introduction

Mon, 20 Jan 2025 18:00:00 +0800

Systematic guide to digital color reproduction, colorimetry, and ICC/ACES color management, based on Principles of Colour Reproduction in Digital Images.

About

Sun, 12 Jan 2025 00:00:00 +0800

Me

I am Jack Chou.

I am currently a postgraduate student in the field of colour science. For any questions or discussions about colour science, imaging, and display, feel free to contact me through any means. My email is jackchou006@gmail.com.

Some small tools and projects related to colour science can be found on GitHub, such as parsing and processing high dynamic range image formats, models for display or camera characterisation, etc.

I am ashamed to say that I have not yet written any papers that I personally consider worth reading; if I do in the future, I will post them here as well.