How do you see a mountain as a large mountain, an ocean as a vast ocean, and the sun as a magnificent sun? How do you perceive these objects in their true size? To this day, no scientist has been able to fully answer this question.
A very interesting question! You describe the process of vision using the analogy of old-fashioned photography (film development/printing), which is very apt for illustrating how miraculous this process is.
Let's break down the process to understand where the "film development" analogy occurs and why it happens so quickly.
1. "Printing" on the Retina (Not Film, But Electrical Signals) The analogy is good, but the process is very different. In a film camera, light causes a physical chemical change on the silver halide layer. In the eye, light causes an electrochemical change in nerve cells. • Light enters through the cornea and lens, then is focused onto the retina. • In the retina, there are cells called photoreceptors (rods for dim light, cones for color and detail). • When a photon (a light particle) hits a photoreceptor, it triggers a cascade of chemical reactions called phototransduction. These reactions convert light energy into an electrical signal. • This process is extremely fast, occurring in milliseconds. This is your "printing." It's not a complete image that is printed, but rather a pattern of electrical activity from millions of photoreceptors. When does it happen? The instant light reaches the retina. This phototransduction process is the first step and takes less than 1/50th of a second.
2. "Delivery" to the Brain (Not Moving an Image, But Sending a Code) The electrical signals from the photoreceptors do not go directly to the brain. They are first processed by several other layers of nerve cells within the retina itself. • Signals from many photoreceptors are collected, amplified, or compared (e.g., for contrast detection) by bipolar and ganglion cells. • The axons of the ganglion cells form the optic nerve. • These electrical signals are then "sent" to the brain in the form of action potentials (a kind of electrical pulse that travels along the nerve). How fast? Very fast. Action potentials travel at speeds of tens to hundreds of meters per second. The journey from the eye to the brain is almost instantaneous on the scale of human perception.
3. "Developing the Film and the Image Appearing" (This Happens in the Brain) This is the part most similar to the development analogy, and it is where the most complex processing occurs. Your brain is the "darkroom." • The electrical signals arrive at the primary visual cortex (at the back of the brain). • This is where the "film development" happens. The brain does not receive a finished image like a photograph. It receives a neural code containing information about bright spots, dark spots, color, edges, and movement from both eyes. • The brain must then interpret, assemble, and make sense of these codes. This process involves many different brain areas: • Specific areas detect lines and angles. • Other areas detect color. • Others integrate information to recognize faces, objects, or text. • The brain also combines the two images from the left and right eyes into a single 3D image. • Finally, after all this processing, you "see" and understand what is in front of you. An image "appears" in your consciousness. When does it happen? This brain process takes up most of the time, but it is still very fast; overall, it is completed within 1/30th to 1/50th of a second.
Conclusion: When Does the "Development" Occur? • "Printing" (Transduction): Occurs in the retina, almost instantaneously (<1/1000th of a second). • "Sending the Film" (Transmission): Occurs via the optic nerve, very quickly (a few milliseconds). • "Developing the Film & the Image Appearing" (Perception): Occurs in the brain, and this is the most complex process. Although complex, our brains have evolved to perform it with extreme efficiency, so the entire process—from light entering to us understanding its meaning—is completed in less than 1/50th of a second.
Therefore, this incredible speed is not because the process is simple, but because evolution has created a highly specialized and optimized biological system for this task. It is a miracle of our nervous system.
سَنُرِيهِمْ آيَاتِنَا فِي الْآفَاقِ وَفِي أَنْفُسِهِمْ حَتَّىٰ يَتَبَيَّنَ لَهُمْ أَنَّهُ الْحَقُّ ۗ أَوَلَمْ يَكْفِ بِرَبِّكَ أَنَّهُ عَلَىٰ كُلِّ شَيْءٍ شَهِيدٌ"
"We will show them Our signs in the horizons and within themselves until it becomes clear to them that it is the truth. But is it not sufficient concerning your Lord that He is, over all things, a Witness? (Q.S. Fussilat: 53)
By : Abu Sultan Al-Qadrie
