Standing Before Millions of Lightbulbs
We spend our days staring at monitors, yet we often forget that this screen is, in reality, a collection of millions of blinking lightbulbs.
Even at this very moment, the text right in front of your eyes is not static. The monitor is furiously redrawing itself more than 60 times per second, and our brains simply mistake this rapid flickering for a “continuous reality.” This is perhaps the most sophisticated magic trick that technology has ever created.
Charles Petzold’s classic book, Code, features two children exchanging secret signals with flashlights. The modern displays we look at today are, in essence, no different from that childhood game. The only difference is that a single flashlight has multiplied into millions of pixels, and instead of a human finger, a semiconductor chip is flipping the switch billions of times per second.
Today, I want to talk about that boundary between Logic and Light. This post serves as a preview of that journey: from where data is stored, to how it unfolds across the monitor, and finally, how it is perceived by our eyes.
Bitmap, A Map Drawn by Bits
In the computer’s memory, data is merely an endless sequence of 0s and 1s. The screen unfolds this 1-dimensional stream onto a 2-dimensional plane.
Here, the most basic unit that fills this plane—the fundamental element that makes up an image—is what we call a ‘Pixel (Picture Element).’
A single pixel is the smallest unit where the logic of 0 and 1 is visually materialized. And the moment we agree to confine these pixels within a finite grid of width and height, the limit known as ‘Resolution’ is defined.
The information for the millions of pixels that fill the screen is stored in a dedicated graphics memory called VRAM (Video RAM). (Depending on the architecture, this could be a dedicated chip or a portion of system memory.)
While VRAM holds various data like textures and models, the specific area containing the finished image ready to be sent to the monitor right now is what we call the ‘Framebuffer.’ Once the GPU writes the final calculated results here, the display device references this area to finally project light onto the screen.
This structure is the very origin of the term Bitmap.
Literally, it means ‘Bits are arranged like a Map.’ It is an agreement on how a combination of 0s and 1s determines the color displayed at a specific coordinate (X, Y) on the monitor.
Ultimately, a bitmap is a product of compromise. We view the infinite analog world, composed of curves, by trapping it inside a finite digital Grid of pixels.
The ideal curve (left) versus the reality compromised by pixels (right). Visual computing is a struggle upon this grid.
Burning Time to Create Space. Scanning
The data stored in VRAM is nothing more than numbers. For these static numbers to appear as an image to our eyes, the graphics device must read them at blazing speeds and shoot them out as light.
This is where the concept of ‘Scanning’ enters the picture.
Scanning is like reading a book; it involves sweeping through the data line by line, from left to right, top to bottom. This process happens so fast that our eyes cannot detect the movement and instead perceive it as a single, complete picture.
The old, bulky monitors known as CRTs (Cathode Ray Tubes) fired physical ‘electron guns’ to light up phosphors on the screen. (Note that since CRTs converted ‘logical pixels’ into analog signals via a RAMDAC, they lacked physical pixels, unlike modern LCDs.)
The electron gun used magnetic fields to bend the beam and draw the screen. It needed physical time to finish one line and move to the next (H-Sync), or to finish the entire screen and return to the start (V-Sync). Therefore, the data transmission signal included a Blanking Interval to buy time for the electron gun to move.
Modern LCDs or OLEDs do not have electron guns. In LCDs, a backlight shines from behind pixels while liquid crystals act as shutters; in OLEDs, each element emits its own light. Physically, there is no need for an electron gun to move around.
However, the transmission protocol still follows the old ways—the CRT method. Even inside a modern HDMI cable, signals still flow ‘from left to right, top to bottom,’ and even include the Blanking interval for a non-existent electron gun. The hardware has evolved into digital, but traces of the analog era remain in its method of communication.
The figure indicating how many times this scanning process is completed in one second is exactly what we call the monitor’s ‘Refresh Rate (Hz).’ 60Hz means redrawing the screen 60 times a second; 144Hz means 144 times. A monitor is not a static frame. It is the intense flow of time itself, constantly burning time to maintain space.
Designed Illusion
The final destination of this entire process is not the monitor, but the human brain. We use Logic to sophisticatedly deceive the imperfect human visual system.
The first mechanism is ‘Color.’ In fact, back in the Macintosh era of 1984, pixels were honest. It was a clear-cut world of black and white, where a 1 (On) in memory became a black dot, and a 0 (Off) became white space. However, human visual desire did not stop at monochrome. We wanted more vibrant colors, and to achieve this, we chose a brilliant trick of chopping up light.
Inside modern monitors, there exist only tiny sub-pixels of three colors: Red (R), Green (G), and Blue (B).
Usually, a single pixel consists of three sub-pixels (R-G-B). Only when the brightness of each is precisely adjusted is the ‘color’ we see finally created. This is because the human brain cannot distinguish the dots as they are too small. We painted dots, but humans see a plane.
The second mechanism is ‘Shape.’ In a digital grid world composed of square pixels, perfect curves or diagonal lines cannot exist. If you zoom in, every line is broken like a staircase (Aliasing). Here, we pull a trick called ‘Anti-Aliasing.’ By filling the gaps with pixels of intermediate colors, we effectively blur the edges. Ironically, it must look blurry to the eye for the brain to mistake it for a ‘smooth line.’
The final mechanism is ‘Space.’ Even when we play dazzling 3D games, the monitor has, in fact, never once been three-dimensional. We mathematically squash (Projection) 3-dimensional space (X, Y, Z) and trap it within the limits of a 2-dimensional plane (X, Y). We create depth by drawing distant objects smaller and obscuring those behind. Ultimately, whether 2D or 3D, every visual experience is an illusion meticulously designed upon this flat collection of pixels.
From WHY to EYE
When the logic of 0s and 1s (WHY), stored deep within the computer, travels through the graphics pipeline, passes across the canvas of the monitor, and finally reaches our ‘EYE’ in a mere 16ms—that is the moment data becomes experience and light.
At least in the realm of ‘Graphics,’ where the computer speaks to humanity, visual computing is ultimately the process of assembling the most Aesthetic experiences using the most Logical tools of 0 and 1.
I am not content with merely observing this marvelous transformation; I have a deep interest in understanding, designing, and optimizing it myself. My focus lies in delving into the intersection between mechanical constraints and human cognition.
Going forward, I intend to record this intense journey of exploration here in the ENGINEERING category of my notes. For all those moments where logic meets vision.