A 45,000 DA phone advertises 108 megapixels. Another one costing five times as much settles for 48. On paper the first wins easily. In a photo taken at night in a living room, the opposite often happens.
A megapixel measures one thing: how many points the sensor can record. It says nothing about how much light is collected, or how the processor turns those points into an image.
What a megapixel actually measures
A 108 MP photo holds 108 million pixels. That allows aggressive cropping, or large prints. For a screen, a social post or a message, 12 million is plenty.
So the number mainly serves cropping. It guarantees neither sharpness, nor colour, nor low-light behaviour.
Pixel binning
On a 108 MP sensor the pixels are tiny. To compensate, the phone combines nine neighbouring pixels into one at capture time. The final photo is then 12 MP, and each point uses information from nine others.
The technique is called pixel binning. It improves brightness and reduces noise. It explains why a 108 MP sensor usually outputs 12 MP photos by default.
A 108 MP mode does exist, but it disables itself as soon as light drops. Indoors the phone returns to 12 MP without telling you. The number on the box describes an exception, not daily use.
Sensor size
Two 108 MP sensors can produce very different results depending on physical size. A 1/1.7 inch sensor gathers far more light than a 1/2.8 inch one, even with the same pixel count.
The larger each pixel, the more photons it collects. A well-sized 12 MP sensor with 1.4 micron pixels easily competes with a 108 MP sensor built on tiny pixels.
Aperture matters too. An f/1.7 lens lets in more light than f/2.2. That difference weighs more on a night photo than ten million extra pixels.
Stabilisation
A very dense sensor magnifies any movement. Without optical stabilisation, handheld shots lose sharpness, especially in the evening.
OIS compensates for hand shake. It helps video as well. A 108 MP phone without OIS often produces blurrier images than a stabilised 12 MP one.
Software processing
The final photo comes out of an image processor. It merges several exposures, corrects exposure, applies noise reduction and tunes colour.
Two devices with the same sensor can produce very different images depending on the quality of that processing. A large part of the gap between mid-range and flagship sits there.
The 108 MP mode in practice
It demands plenty of light. It produces files of 20 to 30 MB, sometimes more. Capture slows down because the sensor must read every row.
On a mid-range phone, the mode mostly impresses in a shop. A 108 MP photo taken at noon on a balcony holds more detail than a 12 MP one. The same scene at 7 pm inside a flat looks noisy.
How to read a spec sheet
Look for sensor size, written as a fraction of an inch. Look for aperture, written f/. Check for optical stabilisation. Finally check video modes: 4K at 60 frames per second needs a solid sensor and processor.
Pixel count comes last. It tells you the maximum resolution, not the image quality.
Test before buying
In a shop, ask to take three photos. One in full light, one near a shaded window, one in a dark corner. Compare them on your own phone, not on the seller's screen, which is often oversaturated.
Test the zoom without moving. Test video while walking. Those three minutes reveal more than the spec sheet.
The short version
A 108 MP sensor can produce excellent photos, provided it is large, stabilised and well processed. On a cheap device the number remains a marketing argument.
Sensor size, aperture, stabilisation and processing decide the result. Megapixels only indicate how much detail you can hope to capture in the best conditions.
