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sRGB vs REC709 – An introduction and FFmpeg implementations
1. Basic Comparison
- What they are
- sRGB: A standard “web”/computer-display RGB color space defined by IEC 61966-2-1. It’s used for most monitors, cameras, printers, and the vast majority of images on the Internet.
- Rec. 709: An HD-video color space defined by ITU-R BT.709. It’s the go-to standard for HDTV broadcasts, Blu-ray discs, and professional video pipelines.
- Why they exist
- sRGB: Ensures consistent colors across different consumer devices (PCs, phones, webcams).
- Rec. 709: Ensures consistent colors across video production and playback chains (cameras → editing → broadcast → TV).
- What you’ll see
- On your desktop or phone, images tagged sRGB will look “right” without extra tweaking.
- On an HDTV or video-editing timeline, footage tagged Rec. 709 will display accurate contrast and hue on broadcast-grade monitors.
2. Digging Deeper
Feature sRGB Rec. 709 White point D65 (6504 K), same for both D65 (6504 K) Primaries (x,y) R: (0.640, 0.330) G: (0.300, 0.600) B: (0.150, 0.060) R: (0.640, 0.330) G: (0.300, 0.600) B: (0.150, 0.060) Gamut size Identical triangle on CIE 1931 chart Identical to sRGB Gamma / transfer Piecewise curve: approximate 2.2 with linear toe Pure power-law γ≈2.4 (often approximated as 2.2 in practice) Matrix coefficients N/A (pure RGB usage) Y = 0.2126 R + 0.7152 G + 0.0722 B (Rec. 709 matrix) Typical bit-depth 8-bit/channel (with 16-bit variants) 8-bit/channel (10-bit for professional video) Usage metadata Tagged as “sRGB” in image files (PNG, JPEG, etc.) Tagged as “bt709” in video containers (MP4, MOV) Color range Full-range RGB (0–255) Studio-range Y′CbCr (Y′ [16–235], Cb/Cr [16–240])
Why the Small Differences Matter
(more…) - What they are
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Narcis Calin’s Galaxy Engine – A free, open source simulation software
This 2025 I decided to start learning how to code, so I installed Visual Studio and I started looking into C++. After days of watching tutorials and guides about the basics of C++ and programming, I decided to make something physics-related. I started with a dot that fell to the ground and then I wanted to simulate gravitational attraction, so I made 2 circles attracting each other. I thought it was really cool to see something I made with code actually work, so I kept building on top of that small, basic program. And here we are after roughly 8 months of learning programming. This is Galaxy Engine, and it is a simulation software I have been making ever since I started my learning journey. It currently can simulate gravity, dark matter, galaxies, the Big Bang, temperature, fluid dynamics, breakable solids, planetary interactions, etc. The program can run many tens of thousands of particles in real time on the CPU thanks to the Barnes-Hut algorithm, mixed with Morton curves. It also includes its own PBR 2D path tracer with BVH optimizations. The path tracer can simulate a bunch of stuff like diffuse lighting, specular reflections, refraction, internal reflection, fresnel, emission, dispersion, roughness, IOR, nested IOR and more! I tried to make the path tracer closer to traditional 3D render engines like V-Ray. I honestly never imagined I would go this far with programming, and it has been an amazing learning experience so far. I think that mixing this knowledge with my 3D knowledge can unlock countless new possibilities. In case you are curious about Galaxy Engine, I made it completely free and Open-Source so that anyone can build and compile it locally! You can find the source code in GitHub
https://github.com/NarcisCalin/Galaxy-Engine
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Introduction to BytesIO
When you’re working with binary data in Python—whether that’s image bytes, network payloads, or any in-memory binary stream—you often need a file-like interface without touching the disk. That’s where
BytesIOfrom the built-iniomodule comes in handy. It lets you treat a bytes buffer as if it were a file.What Is
BytesIO?- Module:
io - Class:
BytesIO - Purpose:
- Provides an in-memory binary stream.
- Acts like a file opened in binary mode (
'rb'/'wb'), but data lives in RAM rather than on disk.
from io import BytesIO
Why Use
BytesIO?- Speed
- No disk I/O—reads and writes happen in memory.
- Convenience
- Emulates file methods (
read(),write(),seek(), etc.). - Ideal for testing code that expects a file-like object.
- Emulates file methods (
- Safety
- No temporary files cluttering up your filesystem.
- Integration
- Libraries that accept file-like objects (e.g., PIL,
requests) will work withBytesIO.
- Libraries that accept file-like objects (e.g., PIL,
Basic Examples
1. Writing Bytes to a Buffer
(more…)from io import BytesIO # Create a BytesIO buffer buffer = BytesIO() # Write some binary data buffer.write(b'Hello, \xF0\x9F\x98\x8A') # includes a smiley emoji in UTF-8 # Retrieve the entire contents data = buffer.getvalue() print(data) # b'Hello, \xf0\x9f\x98\x8a' print(data.decode('utf-8')) # Hello, 😊 # Always close when done buffer.close() - Module:
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Marigold – repurposing diffusion-based image generators for dense predictions
Marigold repurposes Stable Diffusion for dense prediction tasks such as monocular depth estimation and surface normal prediction, delivering a level of detail often missing even in top discriminative models.
Key aspects that make it great:
– Reuses the original VAE and only lightly fine-tunes the denoising UNet
– Trained on just tens of thousands of synthetic image–modality pairs
– Runs on a single consumer GPU (e.g., RTX 4090)
– Zero-shot generalization to real-world, in-the-wild imageshttps://mlhonk.substack.com/p/31-marigold
https://arxiv.org/pdf/2505.09358
https://marigoldmonodepth.github.io/
FEATURED POSTS
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Pallaidium – a free and open source genAI movie studio integrated into the free Blender video editor
https://github.com/tin2tin/Pallaidium/
Features
Text to video Text to audio Text to speech Text to image Image to image Image to video Video to video Image to text ControlNet OpenPose ADetailer IP Adapter Face/Style Canny Illusion Multiple LoRAs Segmind distilled SDXL Seed Quality steps Frames Word power Style selector Strip power Batch conversion Batch refinement of images. Batch upscale & refinement of movies. Model card selector. Render-to-path selector. Render finished notification. Model Cards One-click install and uninstall dependencies. User-defined file path for generated files. Seed and prompt added to strip name. 
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Why the Solar Maximum means peak Northern Lights in 2025
https://northernlightscanada.com/explore/solar-maximum
Every 11 years the Sun’s magnetic pole flips. Leading up to this event, there is a period of increased solar activity — from sunspots and solar flares to spectacular northern and southern lights. The current solar cycle began in 2019 and scientists predict it will peak sometime in 2024 or 2025 before the Sun returns to a lower level of activity in the early 2030s.
The most dramatic events produced by the solar photosphere (the “surface” of the Sun) are coronal mass ejections. When these occur and solar particles get spewed out into space, they can wash over the Earth and interact with our magnetic field. This interaction funnels the charged particles towards Earth’s own North and South magnetic poles — where the particles interact with molecules in Earth’s ionosphere and cause them to fluoresce — phenomena known as aurora borealis (northern lights) and aurora australis (southern lights).
In 2019, it was predicted that the solar maximum would likely occur sometime around July 2025. However, Nature does not have to conform with our predictions, and seems to be giving us the maximum earlier than expected.
Very strong solar activity — especially the coronal mass ejections — can indeed wreak some havoc on our satellite and communication electronics. Most often, it is fairly minor — we get what is known as a “radio blackout” that interferes with some of our radio communications. Once in a while, though, a major solar event occurs. The last of these was in 1859 in what is now known as the Carrington Event, which knocked out telegraph communications across Europe and North America. Should a similar solar storm happen today it would be fairly devastating, affecting major aspects of our infrastructure including our power grid and, (gasp), the internet itself.
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Photography basics: Solid Angle measures
http://www.calculator.org/property.aspx?name=solid+angle
A measure of how large the object appears to an observer looking from that point. Thus. A measure for objects in the sky. Useful to retuen the size of the sun and moon… and in perspective, how much of their contribution to lighting. Solid angle can be represented in ‘angular diameter’ as well.
http://en.wikipedia.org/wiki/Solid_angle
http://www.mathsisfun.com/geometry/steradian.html
A solid angle is expressed in a dimensionless unit called a steradian (symbol: sr). By default in terms of the total celestial sphere and before atmospheric’s scattering, the Sun and the Moon subtend fractional areas of 0.000546% (Sun) and 0.000531% (Moon).
http://en.wikipedia.org/wiki/Solid_angle#Sun_and_Moon
On earth the sun is likely closer to 0.00011 solid angle after athmospheric scattering. The sun as perceived from earth has a diameter of 0.53 degrees. This is about 0.000064 solid angle.
http://www.numericana.com/answer/angles.htm
The mean angular diameter of the full moon is 2q = 0.52° (it varies with time around that average, by about 0.009°). This translates into a solid angle of 0.0000647 sr, which means that the whole night sky covers a solid angle roughly one hundred thousand times greater than the full moon.
More info
http://lcogt.net/spacebook/using-angles-describe-positions-and-apparent-sizes-objects
http://amazing-space.stsci.edu/glossary/def.php.s=topic_astronomy
Angular Size
The apparent size of an object as seen by an observer; expressed in units of degrees (of arc), arc minutes, or arc seconds. The moon, as viewed from the Earth, has an angular diameter of one-half a degree.
The angle covered by the diameter of the full moon is about 31 arcmin or 1/2°, so astronomers would say the Moon’s angular diameter is 31 arcmin, or the Moon subtends an angle of 31 arcmin.
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Matt Gray – How to generate a profitable business
In the last 10 years, over 1,000 people have asked me how to start a business. The truth? They’re all paralyzed by limiting beliefs. What they are and how to break them today:
(more…)
Before we get into the How, let’s first unpack why people think they can’t start a business.
Here are the biggest reasons I’ve found:
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The Color of Infinite Temperature
This is the color of something infinitely hot.
Of course you’d instantly be fried by gamma rays of arbitrarily high frequency, but this would be its spectrum in the visible range.
johncarlosbaez.wordpress.com/2022/01/16/the-color-of-infinite-temperature/
This is also the color of a typical neutron star. They’re so hot they look the same.
It’s also the color of the early Universe!This was worked out by David Madore.
The color he got is sRGB(148,177,255).
www.htmlcsscolor.com/hex/94B1FFAnd according to the experts who sip latte all day and make up names for colors, this color is called ‘Perano’.