How Does A Digital Camera Work? [Technology Explained]

photographers   How Does A Digital Camera Work? [Technology Explained]The digital camera is another great example of a technology we take for granted. Because we had film-based cameras for so long, the idea of capturing an image isn’t that miraculous to us any more. So, with  the natural progression of technology making picture taking more and  more instant, we all seemed to just kind of think, “Of course we can take digital photos.” without questioning how it works.

Except me. I have to know how things work. No good reason for that. Sometimes I have to read a bunch of technical jargon, ask a lot of questions and then relate the information to something else I understand, before I can truly understand what’s going on. That makes me a slow, but tenacious, learner. And really annoying when Jeopardy! is on.

The underlying technology of the digital camera is a light sensor and  a program. The light sensor is most often a Charge Coupled Device  (CCD) and the program is firmware that is embedded right into the circuit board of the camera. Kind of like the programs that help make your microwave oven or iPod work.

I’ll focus on the CCD first. Yes, there is another kind of light sensor that can be used and that’s the Complimentary Metal Oxide Semiconductor (CMOS) type. The mechanics of how they do what they do differ, but the principles are the same.

CCD Image sensor   How Does A Digital Camera Work? [Technology Explained]

Think of the CCD as being a grid of millions of little squares, each one kind of like a solar cell. You know that a solar cell takes light energy and converts it to electrical energy right? And you probably figured that the more light there is the more energy it makes and vice versa right? So you can see where we’re going with this whole CCD thing.

Each of those little squares on the CCD takes light energy and converts it to electrical energy. Each condition of the light ““ like brightness and intensity ““ generates a very specific electrical charge. Those charges for each little square are then transported through an array of electronics to where it can be interpreted by the firmware. The firmware knows what each specific charge means and translates it to information that includes the colour and other qualities of the light that the CCD picked up.

CCD closeup   How Does A Digital Camera Work? [Technology Explained]

This process is done for each of the squares in the grid of the CCD ““ so now you can see the miracle that it really is! Now picture (pun intended) a million little squares, each one different as though they were puzzle pieces. The firmware puts those puzzle pieces together to form an image that is recognizable to the human eye.

The process of putting it together is very much akin to what happens with your television or monitor. It does this using pixels. Each pixel is comprised of three basic colours ““ red, green and blue. By varying the intensity of each colour within a pixel, the variety of colours that can be produced is amazing indeed. This is known as a Bayer filter.

CCD Bayer Filter   How Does A Digital Camera Work? [Technology Explained]

Get up close with your monitor ““ to the point where you can see the pixels individually. Don’t worry, that whole thing about going blind from sitting too close to the TV is an old wives’ tale. Except when it comes to my kids.  You might need a magnifying glass. Neat, huh? Did you see how there were more green pixels than red or blue? That’s because somebody figured out that the eye is not as sensitive to green as it is to red or blue.

Image pixels and screen pixels1   How Does A Digital Camera Work? [Technology Explained]

I digressed. The next step is for the firmware to record the information it saw into digital code. That code can be used to accurately reproduce the picture time and time again. Call it a recipe for that specific moment in time that you captured. Now, that code can be passed to the view screen on the camera, or to a monitor or printer to be reproduced.

And now you know how that all works. Hopefully taking the mystery away hasn’t ruined the experience for you. I hope you enjoyed this high level overview of how these things work.

Are you a digital photo enthusiast? Did this article help you to understand the process better? Share your questions with us in the comments, and I’ll try to answer them.

Photo Credit: ralphbijker

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33 Comments -

0 votes

Chris

Thank you!

I’ve been recently taking pictures with my Olymous digital camera to upload pictures to Daily Booth

This helps me understand the process much better

Saved this as a PDF btw :]

0 votes

Guy McDowell

You’re welcome! Thanks for reading!

0 votes

Brown

Very interesting and amusing subject. I read with great pleasure.

0 votes

Karan

I believe that most sensors, especially in point and shoot cameras and cell phones, are CMOS, because they’re generally smaller and can have a higher concentration of the cells you talk about above within the same area.

Also, the Bayer pattern is used for camera sensors, but monitors are arranged to display simple columns of RGB.

Aside from that, most of what you said for CCD’s applies for CMOS sensors as well.

0 votes

Guy McDowell

You are correct on the Bayer pattern comment. I could have written that part to be more clear about which was for the camera and which was for the monitor.

Based on the research that I was able to do, I concluded that the CCD was most popular. Of course, my resources or I could be wrong!

Glad to hear from you! I think you brought greater clarity to my article.

0 votes

travel wallet

Thanks for clearing my concept on how the digital camera works. I captured a lot of photos but didn’t know how it works. Thanks for sharing.

0 votes

Guy McDowell

You’re very welcome. Checked out the ZoomBits site you listed. Pretty cool. Do you work for them?

0 votes

Kyle

With all respect, Guy, your comment on why there are more more green pixels than red and blue is backwards.

There are more green pixels because the human eye is actually more sensitive to the color “green”. I’m aware that it may seem counter-intuitive. : )

The facts are:
1) The highest intensity visible wavelength of light from our sun is “green”. It makes sense, then that our eyes would have sensitivity to match.

2) Therefore, twice the number of “green” pixels in CCDs help make up a greater fidelity (of the color) so that our eyes “see” and our brain “interprets” a believable rendition of a picture.

I just wanted to point you in this direction. There are plenty of sources if you’re curious!

Also, CMOS sensors are very popular in modern electronics because they are smaller, take less power, and are simpler. CCDs are analog devices that require more electronics to convert the received light intensities to a digital image, introducing less efficiency and more power required. The downside to CMOS sensors are that they don’t do too well in the dark and introduce noise/artifacts. (Have you seen a sloppy camera picture in low-light?)

This is a very nice article and I appreciate you explaining this! Knowing/learning how things work can help us excel in using them. The pictures are helpful too!

0 votes

Guy McDowell

Absolutely correct of course, about the colour green. I should have worded that differently.

0 votes

Pollux

Colors are not captured as such: light information that is captured ends up being processed by the camera. the respective wavelength will then be used to change these very b&w information into colors.
One fantastic site for anybody into photography/techniques : http://www.cambridgeincolour.com/tutorials/camera-sensors.htm

0 votes

Guy McDowell

I think that’s pretty much what I said when I talked about the signal being interpreted by the firmware to determine what the real image is.

The hardest part about writing these articles is to do so in a manner that will make the basic idea accessible to people who are curious, but don’t have any sort of background in the subject. In doing so, things may not be as precise as it would be, say, in a Wikipedia article.

In general, it gets tougher when people who do have background in the subject area come in and leave comments about how something I wrote isn’t strictly correct. I don’t mean you, Pollux, specifically. I’m speaking generally.

That has the unfortunate effect of the layperson dismissing the entire article and still not knowing the basics of a technology. Perhaps they will find articles that target an engineering audience and leave with more confusion than they came with.

0 votes

Chris

Cool,

Glad I could see this article. I was just thinking of this a week or so ago when I read that the guys who invented digital cameras split a nobel prize or some genius award.

0 votes

VivekM

Complementary Metal Oxide Semiconductor …

0 votes

Guy McDowell

You mean your CMOS doesn’t say nice things to you? Maybe you should buy it some flowers now and again. ;)

0 votes

Tony Bampfield

Guy

Does a 12 megapixel camera have 12 X 10**6 “little squares”
in the CCD?

Tony