WEBVTT - How Image Sensors Work 0:00:00.280 --> 0:00:02.920 Brought to you by the reinvented two thousand twelve Camray. 0:00:03.160 --> 0:00:08.880 It's ready. Are you get in touch with technology with 0:00:08.960 --> 0:00:17.360 tex Stuff from how stuff works dot com. Hello, and 0:00:17.480 --> 0:00:20.320 welcome to tex Stuff. My name is Chris Poulette and 0:00:20.320 --> 0:00:22.759 I am an editor at how stuff works dot com, 0:00:22.800 --> 0:00:25.320 sitting in a cross froom me as usual as senior 0:00:25.360 --> 0:00:29.320 writer Jonathan Strickland. Psychics can see the color of time. 0:00:29.840 --> 0:00:35.320 It's blue. Okay, I'd kind of love to know what 0:00:35.320 --> 0:00:38.120 what that one's from. I'll tell you. I'll tell you 0:00:38.159 --> 0:00:40.440 after the show if you remind me, alright, I always 0:00:40.520 --> 0:00:42.760 say that I'll tell you, and I never tell you 0:00:42.920 --> 0:00:45.040 because I always forget by the time we're done recording. 0:00:45.440 --> 0:00:48.199 Tell me what there's the trivia for you, folks. So 0:00:48.240 --> 0:00:50.879 today we thought we would look at something. Actually, it 0:00:50.960 --> 0:00:54.560 was Chris's suggestion that we look into this particular topic, 0:00:54.920 --> 0:00:59.520 which was the the topic of image sensors and what 0:00:59.560 --> 0:01:03.320 they do and what the two main types of image sensors, 0:01:03.360 --> 0:01:06.640 how they are different from one another, and uh, and 0:01:06.680 --> 0:01:08.880 I thought it was a great idea. It's also a 0:01:08.880 --> 0:01:11.959 fairly complex topic. We do have an article on how 0:01:12.040 --> 0:01:14.559 stuff works dot com that says what is the difference 0:01:14.640 --> 0:01:17.880 between c c D and CMO s image sensors in 0:01:17.880 --> 0:01:20.399 a digital camera. And that's really what we're gonna be 0:01:20.400 --> 0:01:23.400 talking about here. Um. So that there is an article 0:01:23.400 --> 0:01:25.280 on the site, and it's a nice short article if 0:01:25.280 --> 0:01:27.119 you want a quick overview, but we're gonna go into 0:01:27.160 --> 0:01:30.720 some detail a little bit in this podcast. And really 0:01:31.600 --> 0:01:33.440 the first thing you need to know is that an 0:01:33.480 --> 0:01:38.520 image sensor is it's taking the place of film, right, Yes, 0:01:38.600 --> 0:01:40.600 that's correct. Yeah, a long and long time ago in 0:01:40.640 --> 0:01:42.840 a galaxy that happens to be right here where we're sitting. 0:01:43.520 --> 0:01:49.040 We did a podcast on the megapixel myth um. I 0:01:50.040 --> 0:01:53.680 think a lot of people equate uh numbers with a 0:01:53.720 --> 0:01:56.280 way too yeah, with quality, and they say, oh, well, 0:01:56.280 --> 0:01:59.280 I've got a twelve megapixel camera that's obviously better than 0:01:59.320 --> 0:02:02.160 that six make a pixel camera I used to own. Well, 0:02:02.440 --> 0:02:05.280 it depends on what you're doing with the photo. It 0:02:05.320 --> 0:02:09.639 also depends on again the other qualities of that camera, right, 0:02:09.720 --> 0:02:12.600 and image sensors have a lot more to do with 0:02:13.440 --> 0:02:17.200 the quality of the photo. But in a way it 0:02:17.280 --> 0:02:21.720 really depends because again this uh there, there's this this 0:02:21.840 --> 0:02:24.720 idea that there are two different kinds which kind is better. 0:02:25.160 --> 0:02:28.440 It depends on what you're doing with that, what are 0:02:28.480 --> 0:02:33.000 you taking photos of? UM and uh, as it turns out, 0:02:33.360 --> 0:02:37.640 they're they're not really better than one another. Inherently, they're 0:02:37.639 --> 0:02:41.720 they're better than one another for specific applications of the 0:02:41.800 --> 0:02:45.840 photographic technology, and the quality of the two sensors is 0:02:45.919 --> 0:02:49.520 constantly getting closer and closer, so that the things that 0:02:49.600 --> 0:02:52.639 one sensor does better than the other start to become 0:02:52.720 --> 0:02:56.359 less distinct over time because the technology is improving on 0:02:56.440 --> 0:03:01.440 both sides simultaneously. Uh. If we were to go back 0:03:01.480 --> 0:03:03.880 a little bit to the early days of digital cameras, 0:03:04.360 --> 0:03:08.399 the distinction was was clear. You know, you would say that, well, 0:03:08.440 --> 0:03:11.880 a professional photographer would more likely have a cc D 0:03:12.800 --> 0:03:15.919 image sensor in his or her camera c c D 0:03:16.120 --> 0:03:19.799 meaning charge coupled device, charge coupled device, that's that's one 0:03:19.800 --> 0:03:23.640 of the two types. And someone who has say a 0:03:23.760 --> 0:03:26.760 relatively inexpensive of course, back in the early day of 0:03:26.800 --> 0:03:31.119 digital cameras, that was definitely relatively eight billion dollars, only 0:03:31.160 --> 0:03:36.520 a thousand, princely going back to that a thousand dollars 0:03:36.520 --> 0:03:41.200 as opposed to say eight thousand dollars. But a person 0:03:41.280 --> 0:03:44.760 holding one of those cameras might have a CMOS or 0:03:44.760 --> 0:03:50.200 a complementary metal ox side semiconductor image sensory. They come 0:03:50.240 --> 0:03:53.280 up and say, that's a wonderful shirt you're wearing today. 0:03:53.360 --> 0:03:56.440 That's such a great picture you've taken. Have you lost weight? No, 0:03:56.560 --> 0:03:58.680 it's not that kind of complimentary. I have a whole 0:03:58.760 --> 0:04:00.880 joke about that, but I'm going to everybody because we've 0:04:00.880 --> 0:04:05.000 already said the punchline. Anyway, these are the two different sensors, 0:04:05.160 --> 0:04:08.600 and they do go about capturing data a different way. 0:04:09.120 --> 0:04:12.520 Let's let's go into the basic way a camera captures 0:04:12.600 --> 0:04:15.920 an image. I'm going to talk about still camera here. Okay, 0:04:15.960 --> 0:04:19.080 so we're talking about cameras in general, not necessarily film 0:04:19.200 --> 0:04:22.880 or digital. Right, So, in general, what happens is you've 0:04:22.880 --> 0:04:25.120 got a camera and you're pointing it at something that 0:04:25.160 --> 0:04:27.760 you want to take a photo of. Light is coming 0:04:27.960 --> 0:04:32.240 towards you. It's reflecting off of the the subject of 0:04:32.320 --> 0:04:36.400 your photo. If light we're not reflecting off the subject 0:04:36.440 --> 0:04:38.479 of your photo, it would either mean you were in 0:04:38.560 --> 0:04:41.080 total darkness, in which case taking a photo is not 0:04:41.200 --> 0:04:43.800 very helpful, or you're taking a picture of a black 0:04:43.839 --> 0:04:48.080 hole because not even light can escape it. That being said, 0:04:48.080 --> 0:04:50.919 they're actually looking at making a physical picture of a 0:04:50.920 --> 0:04:54.719 black hole using radio telescopes, which is so cool. That's 0:04:54.720 --> 0:04:58.800 a tangent. Anyway, so light is coming from the subject 0:04:59.480 --> 0:05:02.800 is some We should do a full podcast just on that. 0:05:03.120 --> 0:05:06.039 But anyway, lights coming from from the subject towards the 0:05:06.040 --> 0:05:10.159 camera and uh, and the light passes through the lens. 0:05:10.200 --> 0:05:12.360 The purpose of the lens is to focus that light 0:05:12.560 --> 0:05:16.120 toward a specific point within the camera. It moves through 0:05:16.160 --> 0:05:18.599 the aperture, which is the opening behind the lens that 0:05:18.640 --> 0:05:23.239 allows light to pass through. There's a shutter that's there 0:05:23.279 --> 0:05:27.400 behind the aperture which actually directs the light up towards 0:05:27.440 --> 0:05:29.960 the view finder. For the old style cameras, you know, 0:05:29.960 --> 0:05:31.960 the ones that don't have the you know, you're not 0:05:32.000 --> 0:05:34.880 looking at a screen on the back, you're looking actually 0:05:34.880 --> 0:05:37.800 through a view finder. Well, that light gets directed up 0:05:37.800 --> 0:05:42.120 by a mirror that's essentially attached to the shutter that 0:05:43.400 --> 0:05:45.839 makes the light go up inside the camera. Then it 0:05:45.880 --> 0:05:49.880 hits a prism which inverts the light. Because you may 0:05:50.120 --> 0:05:52.479 not know this, but the light the image that's coming in. 0:05:52.520 --> 0:05:56.120 That's saying the sensor is actually upside down from our perspective. Gasp. 0:05:56.360 --> 0:05:58.680 So if you didn't have that prism there, the subject 0:05:58.680 --> 0:06:01.039 you're looking at would be upside down. It would be 0:06:01.080 --> 0:06:05.440 like everything you're taking photos of was in Australia, unless 0:06:05.440 --> 0:06:08.880 you're Australian, in which case it's all in Detroit. So 0:06:09.440 --> 0:06:12.240 that's that's way. If you're wondering why there's all these 0:06:12.279 --> 0:06:15.960 giant car factories in Australia, it's not. It's just because 0:06:16.000 --> 0:06:19.400 you didn't have that there, right, Um, Okay, that's a 0:06:19.520 --> 0:06:22.440 terrible joke, but no, the prism does invert the light, 0:06:23.520 --> 0:06:28.680 so otherwise again upside down. So when you press the 0:06:29.480 --> 0:06:33.799 button to capture an image, the shutter, the shutter release exactly, 0:06:33.800 --> 0:06:36.720 the shutter, the shutter moves out of the way. Instead 0:06:36.760 --> 0:06:38.839 of the light hitting that mirror and going up to 0:06:38.839 --> 0:06:42.919 the prism and inverting the light hits either film in 0:06:42.920 --> 0:06:47.000 a film camera or an image sensor in a digital camera. 0:06:47.880 --> 0:06:50.000 So really the shutter just moves out of the way 0:06:50.360 --> 0:06:53.040 and then the light hits the sensor and then you're 0:06:53.080 --> 0:06:56.000 good to go. It's a little different with the digital 0:06:56.040 --> 0:06:58.640 cameras that are out right now, but that's in general 0:06:58.680 --> 0:07:02.640 how the process works. The basics. Yeah, now, and with 0:07:02.760 --> 0:07:06.839 cameras now, light maybe hitting the sensor constantly, and the 0:07:06.880 --> 0:07:10.840 shutter itself is not a physical shutter. It's just the 0:07:10.840 --> 0:07:15.440 way that the sensory captures data. And we'll talk about 0:07:15.480 --> 0:07:18.320 that when we get to that point. There are two 0:07:18.360 --> 0:07:20.679 different major types of shutters that we can talk about. 0:07:21.680 --> 0:07:24.800 So that's the general process. Now, with film, it's a 0:07:24.960 --> 0:07:28.000 chemical process. Light hits the film and then some chemical 0:07:28.120 --> 0:07:30.960 reactions take place, and that's what allows you to capture 0:07:30.960 --> 0:07:37.200 an image. Right. With image sensors, it's not chemical, it's electrical. Right, 0:07:37.240 --> 0:07:41.880 you're converting light energy into an electronic signal, yes, which 0:07:41.920 --> 0:07:46.360 then you're gonna want to store to some medium. Yes, uh, 0:07:46.520 --> 0:07:50.760 you know, typically some kind of flash memory device, depending 0:07:50.800 --> 0:07:54.120 on on what kind of camera you have. You know, 0:07:54.200 --> 0:07:57.080 there were some I think that that stored on CD, 0:07:57.960 --> 0:08:00.640 so you know, your mileage may vary, but in general, 0:08:00.720 --> 0:08:03.080 some sort of flash device on on today's cameras. Yeah, 0:08:03.120 --> 0:08:08.119 the old digital camcorders could record on on different kinds 0:08:08.120 --> 0:08:12.080 of media and so, and digital camcorders are working under 0:08:12.120 --> 0:08:16.960 the same general principles as digital still cameras, with some 0:08:17.280 --> 0:08:19.400 you know, other differences, but we'll talk about that. Like 0:08:19.440 --> 0:08:22.680 I said, so now we get into the differences between 0:08:22.720 --> 0:08:26.040 the two major types of sensors, the charge coupled device 0:08:26.120 --> 0:08:29.840 and the complementary metal oxide semiconductor. So we're just gonna 0:08:29.880 --> 0:08:33.120 go do cc D and CMOS from here on out, 0:08:33.200 --> 0:08:36.360 I think, otherwise I'm just going to have tongue twisters 0:08:36.400 --> 0:08:38.040 for the rest of the podcast. Yes, well, I just 0:08:38.040 --> 0:08:39.600 wanted to make sure that people knew what it what 0:08:39.720 --> 0:08:43.240 it stood for, obviously very important. So in in a 0:08:43.280 --> 0:08:49.480 CCD sensor, every single pixel now, pixel, remember, is a 0:08:49.520 --> 0:08:53.280 point of light. An image is made up of pixels, 0:08:53.720 --> 0:08:57.360 millions of pixels. That's where the megapixel comes from. Right, 0:08:57.520 --> 0:09:01.640 So a twelve megapixel camera is going to take twelve 0:09:01.840 --> 0:09:06.320 megapixels worth of pixels and within the dimensions of that image, 0:09:07.240 --> 0:09:10.840 whereas an eight megapixel camera will use fewer pixels for 0:09:10.920 --> 0:09:15.080 that same size. Right. But and that's where our idea 0:09:15.120 --> 0:09:18.040 about resolution comes in. Sometimes you hear people talk about 0:09:18.080 --> 0:09:21.560 a low resolution image, it may be that it's got 0:09:21.640 --> 0:09:26.360 fewer pixels in that image so that you can actually 0:09:26.360 --> 0:09:29.040 start seeing if if the pixels are large enough and 0:09:29.120 --> 0:09:32.439 few enough, you can start seeing the borders from one 0:09:32.480 --> 0:09:36.160 pixel to the next. It's not very smooth, it's almost jagged. Well, yeah, 0:09:36.200 --> 0:09:39.200 I mean that this is the benefit of having a 0:09:39.280 --> 0:09:43.400 high megapixel camera. If you shoot it high quality, then 0:09:43.440 --> 0:09:47.600 you are capturing more more pixels for a specific region 0:09:47.800 --> 0:09:51.200 of the image, and you can you can render that 0:09:51.360 --> 0:09:56.720 photo in a larger format. Um because when you shrink, 0:09:57.200 --> 0:09:59.040 when you when you compress the size of a photo 0:09:59.120 --> 0:10:03.000 and reduce it in size um, the computer is able to, 0:10:03.600 --> 0:10:06.720 you know, throw out unnecessary information and that the image 0:10:06.760 --> 0:10:10.480 still is pretty good looking. When you try to increase 0:10:10.559 --> 0:10:13.840 the size, the computer has to sort of guess on 0:10:14.040 --> 0:10:16.160 you know, pixel by pixel basis. Well, I mean, this 0:10:16.240 --> 0:10:19.040 color is sort of a brown color. It looks like 0:10:19.040 --> 0:10:21.160 I could throw something else in here similar. And that's 0:10:21.160 --> 0:10:24.440 why when you increase the size of a photo, a 0:10:24.520 --> 0:10:27.520 digital photo, that it starts to look kind of jaggedy 0:10:27.720 --> 0:10:30.640 and rough because the computer is having to guess at 0:10:30.679 --> 0:10:32.800 what that information is. So if you take a ten 0:10:32.880 --> 0:10:36.640 megapixel photo and shrink it down, it's it's gonna look 0:10:36.640 --> 0:10:38.480 pretty good. But if you try to take a two 0:10:38.520 --> 0:10:41.200 megapixel photo and blow it up, it's not gonna be 0:10:41.320 --> 0:10:44.160 so pretty. Yeah. If you think about it like a puzzle, 0:10:44.440 --> 0:10:46.600 Let's say that you have a puzzle that has four 0:10:46.640 --> 0:10:48.880 pieces to it, well, then you're gonna be able to 0:10:48.920 --> 0:10:51.760 see the division of those those four pieces very clearly. 0:10:52.520 --> 0:10:57.240 If it has four million pieces, then it's each of 0:10:57.240 --> 0:11:01.160 those pieces are individually much tinier than those for giant ones. 0:11:01.440 --> 0:11:03.680 And so the other issue is that the larger you 0:11:03.760 --> 0:11:06.520 blow something up, if it's if it doesn't have enough 0:11:06.559 --> 0:11:10.080 mega pixels in it, not megapixels, but enough pixels, then 0:11:10.160 --> 0:11:13.120 you're gonna start to notice. But that being said, uh, 0:11:13.200 --> 0:11:15.520 the general digital cameras that are out there for the 0:11:15.559 --> 0:11:19.439 consumer market and the general way the consumers use digital cameras, 0:11:19.600 --> 0:11:22.400 megapixels really don't matter because most of us are not 0:11:22.440 --> 0:11:25.480 blowing images up to poster size. Most of us are 0:11:25.559 --> 0:11:29.040 using them for online photo albums. We might print a 0:11:29.080 --> 0:11:31.480 few out, but usually eight by ten tends to be 0:11:31.520 --> 0:11:34.640 about the largest because most people don't have printers capable 0:11:34.679 --> 0:11:38.319 of printing at a larger size, take it to somebody 0:11:38.320 --> 0:11:41.320 to have it printed. It's kind of expensive, so a poster. 0:11:41.600 --> 0:11:43.600 Most of us don't do that, So most of us 0:11:43.640 --> 0:11:47.120 don't need to worry about megapixels at this point. Professional photographers, 0:11:47.120 --> 0:11:51.000 it's a different story. So cc D sensor each of 0:11:51.040 --> 0:11:55.040 those pixels has a charge. The photons that are coming 0:11:55.040 --> 0:11:58.680 in and hitting that image sensor are being transferred from 0:11:58.679 --> 0:12:05.679 from a light inner g from photons into electrons. Now UH, 0:12:06.000 --> 0:12:08.520 they have UH there's an output node with a c 0:12:08.720 --> 0:12:12.959 c D sensor where that is converted into voltage. It's 0:12:13.080 --> 0:12:18.080 buffered and then sent to a different part of the 0:12:18.200 --> 0:12:22.480 camera so that it will become an analog signal. So 0:12:22.520 --> 0:12:25.600 a c c D sensor it's a very it's a 0:12:25.679 --> 0:12:30.440 very UH specific device that doesn't it doesn't have a 0:12:30.440 --> 0:12:33.040 lot of other functionality to it apart from the fact 0:12:33.080 --> 0:12:37.320 that it's taking in light and converting it into voltage. UH. 0:12:38.000 --> 0:12:42.880 Now the pixel is completely devoted to capturing light and 0:12:43.000 --> 0:12:47.120 it has a very uniform output. So the that's that's 0:12:47.160 --> 0:12:50.280 sort of where the the idea of CCD being high 0:12:50.360 --> 0:12:54.480 quality came from. UH. It was very good at capturing 0:12:55.800 --> 0:12:59.040 the true essence of whatever it is you're pointing your 0:12:59.040 --> 0:13:00.959 camera at. You don't have to have you don't have 0:13:01.000 --> 0:13:03.439 to worry about low lighting effects that kind of stuff, 0:13:03.679 --> 0:13:06.559 or or having uh an image turn out too grainy 0:13:06.600 --> 0:13:09.160 if the light is too low, which can happen with 0:13:09.520 --> 0:13:15.280 CMOS images, particularly from a few years ago. It's a 0:13:16.080 --> 0:13:19.640 depending on where you know where the manufacturer for your 0:13:19.679 --> 0:13:24.240 camera got the c m O S sensor. Uh, you 0:13:24.320 --> 0:13:27.840 might not have as big an issue taking low lighting 0:13:28.040 --> 0:13:31.200 up images. But if you've ever used a digital camera 0:13:31.640 --> 0:13:33.640 in a you know, either a dark or just a 0:13:33.720 --> 0:13:37.200 dem environment, and you look like this just doesn't look good. Now, 0:13:37.240 --> 0:13:39.240 when I take a photo outside in the middle of 0:13:39.240 --> 0:13:45.400 the daytime, it looks gorgeous, beautiful colors, very very distinct um. 0:13:45.480 --> 0:13:48.400 That's part of the problem is that the CMOS sensor 0:13:48.559 --> 0:13:51.680 captures it in a different way. In that case, every 0:13:51.679 --> 0:13:56.600 single pixel has its own charge to voltage conversion. The 0:13:56.640 --> 0:13:58.880 c c D it's doing all of the pixels at once, 0:13:59.240 --> 0:14:02.920 and c m OS it's doing each pixel individually. And 0:14:03.000 --> 0:14:07.480 then the sensor itself has other elements added to it 0:14:08.000 --> 0:14:10.760 that the c c D sensor does not have. Remember 0:14:10.800 --> 0:14:14.359 we said c c D kind of offloads the information 0:14:14.400 --> 0:14:20.200 once it's been converted into electrical impulses to other chips, right, Well, 0:14:20.240 --> 0:14:24.040 those elements are actually on a CMO S sensor. So 0:14:24.080 --> 0:14:28.400 it's got amplifiers, it's got digitization circuits, so it's actually 0:14:28.440 --> 0:14:32.840 converting the electricity into bits on the sensor itself. It's 0:14:32.840 --> 0:14:38.120 got noise reduction capabilities. And so that means that it 0:14:38.120 --> 0:14:41.600 actually speeds up the process and it decreases the amount 0:14:41.600 --> 0:14:44.240 of space you need within a camera because all of 0:14:44.240 --> 0:14:46.520 those elements are found on a single chip as opposed 0:14:46.560 --> 0:14:54.920 to having dedicated chips for these these specific functions. Unfortunately, 0:14:55.040 --> 0:14:57.440 also reduces the amount of space it has for image 0:14:57.440 --> 0:15:00.480 capture because all that stuff is on the same chip. Yes, 0:15:00.520 --> 0:15:03.200 so that that you know, that's a downside of it, Yes, 0:15:03.600 --> 0:15:07.520 so you that was one of the arguments again early on, 0:15:07.680 --> 0:15:12.920 was that c c D cameras could take sharper photos 0:15:13.000 --> 0:15:16.920 than CMOS cameras, and that you know, it's almost there 0:15:16.960 --> 0:15:20.960 was also an expense issue, right, c c D image 0:15:20.960 --> 0:15:26.440 sensors tend to be more expensive than c MS ones CMOS. 0:15:26.600 --> 0:15:31.480 The process of manufacturer got so efficient that the price 0:15:31.520 --> 0:15:34.200 started to come down, and that that's why those are 0:15:34.240 --> 0:15:37.640 the sort of image sensors that you find in things 0:15:37.680 --> 0:15:41.400 like smartphones. You know, smartphones that have cameras tend to 0:15:41.440 --> 0:15:44.400 have CMOS sensors in them. They take up less space, 0:15:44.440 --> 0:15:47.160 they put out less heat, they take less energy to 0:15:47.320 --> 0:15:51.360 run um and they're very fast. So those are all 0:15:51.400 --> 0:15:54.400 the qualities that people who are having a who wants 0:15:54.440 --> 0:15:57.120 something in a nice slim form factor or if that's 0:15:57.200 --> 0:16:01.880 what's important to them. So yeah, CCDC image sensor might 0:16:01.920 --> 0:16:06.920 take a sharper quality photo in certain situations, but it's 0:16:06.960 --> 0:16:09.680 also going to require a larger form factor, and it 0:16:09.720 --> 0:16:13.480 does take more energy to run, and that that energy 0:16:13.600 --> 0:16:16.840 is going to also mean more heat because as we know, 0:16:16.960 --> 0:16:19.720 as electricity runs through a circuit, one of the by 0:16:19.800 --> 0:16:22.680 products is heat. We haven't figured out a way to 0:16:22.720 --> 0:16:25.480 get around that yet. It's just one of those one 0:16:25.480 --> 0:16:30.239 of those realities that it's uh um. Basically it's inefficient 0:16:30.360 --> 0:16:32.320 enough where some of the energy is being converted to 0:16:32.360 --> 0:16:35.760 heat energy instead of you know, what it is intended for. 0:16:37.600 --> 0:16:41.720 So so now we've got down to the the idea 0:16:41.840 --> 0:16:46.560 of these two different image sensors capturing uh information in 0:16:47.040 --> 0:16:52.320 different ways um, and the fact that over time both 0:16:52.480 --> 0:16:56.440 both types of sensors have developed to the point where 0:16:56.480 --> 0:16:59.840 the differences between the two, apart from the fundamental difference 0:16:59.840 --> 0:17:05.320 of how they collect information, have started to to diminish. Right, 0:17:05.440 --> 0:17:08.640 so that you can find some professional cameras out there 0:17:08.680 --> 0:17:12.480 now that you CMOS image sensors, whereas you know, a 0:17:12.520 --> 0:17:15.760 few years ago that was really unheard of, and you 0:17:15.760 --> 0:17:20.960 can also find some consumer cameras, especially in the cam 0:17:21.040 --> 0:17:24.800 Quorter realm, that are using cc D image sensors, which 0:17:24.840 --> 0:17:27.400 again for a while you just didn't hear about because 0:17:27.480 --> 0:17:30.320 c c D cameras were so expensive. It was pretty 0:17:30.400 --> 0:17:35.560 much reserved for professionals, you know, just consumers just didn't 0:17:35.600 --> 0:17:37.760 necessarily have the money to drop on something like that 0:17:37.880 --> 0:17:43.240 unless they were you know, one per centers. So yeah, 0:17:43.280 --> 0:17:47.160 it's it's it's it's still a developing thing and we're 0:17:47.200 --> 0:17:50.399 still seeing that kind of level out. But that and 0:17:50.440 --> 0:17:53.480 the two technologies do still exist. They coexist, so it's 0:17:53.480 --> 0:17:56.879 not like one has been abandoned on top of in 0:17:56.920 --> 0:17:59.880 favor of the other, although that tends to their bit, 0:18:00.040 --> 0:18:04.359 there's usually someone predicting that every few years. Well sure sure, 0:18:04.840 --> 0:18:06.640 um yeah. A lot of the research that I did 0:18:06.640 --> 0:18:10.240 for the podcast was from Teleedian Do also which makes 0:18:10.440 --> 0:18:12.600 which makes both types of sensors, and they had some 0:18:12.680 --> 0:18:18.120 really interesting, uh comparative white papers and other information if 0:18:18.119 --> 0:18:20.520 you're interested in getting into the depths of it. It 0:18:20.600 --> 0:18:24.160 got some of it got fairly complicated, um, but basically 0:18:24.200 --> 0:18:28.040 they had one paper that said that they're the image 0:18:28.080 --> 0:18:34.960 sensors can be measured on basically eight different characteristics UM. 0:18:35.119 --> 0:18:39.040 And these were responsivity, you know, basically how responsive that 0:18:39.200 --> 0:18:47.359 the sensor is. Uh, it's dynamic range, uniformity, shuttering, UM, speed, windowing, 0:18:47.760 --> 0:18:51.359 and anti blooming UM. And you know, again this is 0:18:51.400 --> 0:18:55.240 kind of you know complex, but the the UH, it's 0:18:55.280 --> 0:18:59.320 kind of funny because the way that the image sensor 0:18:59.720 --> 0:19:03.280 cap information UM, you know, depending on the type that 0:19:03.320 --> 0:19:08.200 you're talking about, they're not really uh, it's really application specific. 0:19:08.680 --> 0:19:11.400 UM some of them. Some of them really don't have 0:19:11.760 --> 0:19:15.400 that much difference over the others. Like, for example, UM, 0:19:15.600 --> 0:19:19.800 CMOS chips are known to be a little bit more responsive. UM. 0:19:19.840 --> 0:19:22.840 But c c D s are have an advantage in 0:19:22.920 --> 0:19:25.879 dynamic range. But basically they didn't say, you know, the 0:19:26.280 --> 0:19:29.280 this one chip is better than the others. They said 0:19:29.280 --> 0:19:31.720 it has more to do with the manufacturing capability and 0:19:31.720 --> 0:19:33.960 whether the chip has done right and is used in 0:19:34.000 --> 0:19:37.240 their correct setting than it does UM, you know, for 0:19:37.359 --> 0:19:40.560 a particular type of technology. Right. And you were mentioned 0:19:40.680 --> 0:19:44.240 mentioning the fact that there are different shutters. In general, 0:19:44.560 --> 0:19:50.200 a CMOS image sensor uses a rolling shutter. UH. There's 0:19:50.200 --> 0:19:52.480 nothing saying that it couldn't use the same sort of 0:19:52.480 --> 0:19:55.879 shutter that sc D image sensor does, which is a 0:19:55.920 --> 0:19:58.959 global shutter. There's nothing saying that it couldn't. It's just 0:19:59.040 --> 0:20:03.919 that all the camcorders I looked at specifically because this 0:20:04.000 --> 0:20:07.760 really plays more into video than than uh, still photography. 0:20:07.760 --> 0:20:12.080 Although there's some crossover between the two. Um it said 0:20:12.080 --> 0:20:14.960 that you could have a CMOS with a global shutter. 0:20:15.000 --> 0:20:17.800 It's just that you don't find those so once they're 0:20:17.840 --> 0:20:20.440 between the global shutter and a rolling shutter, well, a 0:20:20.560 --> 0:20:23.840 rolling shutter to me, when I the first I read 0:20:23.840 --> 0:20:26.560 about this, the first thing I thought about was, UM 0:20:27.080 --> 0:20:31.439 a copier or a scanner where the image sensor you 0:20:31.480 --> 0:20:35.000 put the document on the on the screen, you close 0:20:35.080 --> 0:20:38.280 the UM the top the lid, and you tell it 0:20:38.320 --> 0:20:39.560 to go ahead and make a copy or make a 0:20:39.600 --> 0:20:42.159 scan of it, and the image sensor travels down the 0:20:42.240 --> 0:20:44.359 length of the document from the top to the bottom 0:20:44.440 --> 0:20:48.240 or you know however exactly and and it is going 0:20:48.640 --> 0:20:51.359 you know, from it's starting at a specific point and 0:20:51.480 --> 0:20:54.800 capturing the entire document as it travels the length of it. 0:20:54.880 --> 0:20:58.119 And uh, you know, because it's going essentially line by 0:20:58.200 --> 0:21:00.560 line if you think about that. In pixel tern is 0:21:00.600 --> 0:21:02.359 taking a row of pixels and then another row of 0:21:02.400 --> 0:21:04.800 pixels and then you know, as it goes down right. Yeah, 0:21:04.800 --> 0:21:07.840 I was thinking of it sort of the way television works. Yes, 0:21:07.880 --> 0:21:12.040 where it'll it'll you have a line by line from 0:21:12.080 --> 0:21:16.960 the top to the bottom. Um will ignore the interpalation part, 0:21:17.440 --> 0:21:20.160 otherwise we have to get really complicated. But anyway, the 0:21:20.400 --> 0:21:23.120 image is painted essentially on your screen from the top 0:21:23.160 --> 0:21:25.119 to the bottom at a rate that's so fast that 0:21:25.200 --> 0:21:27.040 your eye does not detect that. It looks like it's 0:21:27.040 --> 0:21:30.680 all simultaneously projected to you, but it's actually done line 0:21:30.680 --> 0:21:32.080 by line from the top of the screen to the 0:21:32.080 --> 0:21:34.320 bottom of the screen. Same thing with a rolling shutter. 0:21:34.720 --> 0:21:38.160 So when you take a photo or you're using a camcorder. 0:21:38.240 --> 0:21:41.680 Let's stick with camcorders. So if you're using a camcorder 0:21:41.680 --> 0:21:44.760 that has a rolling shutter type of image sensors, we're 0:21:45.000 --> 0:21:49.359 talking cmos. Uh, the the images being recorded from the 0:21:49.400 --> 0:21:53.280 top to the bottom over and over and over again. Okay, 0:21:53.320 --> 0:21:57.399 so uh with a cc D camera, it's a global shutter, 0:21:57.440 --> 0:22:00.560 which means that it's capturing all that data all at once. Yes, 0:22:00.800 --> 0:22:03.680 sort of like film would. Yeah, so it's not it's 0:22:03.680 --> 0:22:07.000 not um, you know, it's not something that's gonna be scrolling. 0:22:07.040 --> 0:22:09.520 It's all one image. So this means that the two 0:22:09.560 --> 0:22:13.920 different types of image sensors are also prone to two 0:22:13.960 --> 0:22:19.280 different kinds of flaws that can happen when you're using them. Well, 0:22:19.320 --> 0:22:21.840 of course, I mean that's that's like any other types 0:22:21.880 --> 0:22:24.800 of technology. Not everything is suited for every use, right, 0:22:25.160 --> 0:22:28.439 So let's say that let's i'll talk about the different 0:22:28.440 --> 0:22:31.400 flaws that you can find. C c D essentially has 0:22:31.720 --> 0:22:35.600 one type of flaw that you can encounter, which is 0:22:35.640 --> 0:22:41.840 called the smear effect. So smearing is let's say that 0:22:41.880 --> 0:22:45.440 you've got a a you're taking an image of something 0:22:45.440 --> 0:22:49.520 that has a bright light in it. Um Smearing is 0:22:49.560 --> 0:22:55.200 this effect where you sort of see the light. You'll 0:22:55.240 --> 0:22:57.880 see like a projection of light above and below it, 0:22:58.200 --> 0:23:00.960 or you know it's that's that's why it's called smears. 0:23:01.040 --> 0:23:04.560 It's been extended beyond just a source of light itself. 0:23:05.359 --> 0:23:08.240 It's kind of like a halo effect, though usually it's 0:23:08.280 --> 0:23:11.679 more of at least in the samples I've looked at, 0:23:11.760 --> 0:23:14.159 it's more of a vertical thing where it looks like 0:23:14.160 --> 0:23:16.920 it's almost like a ray of light that goes straight 0:23:17.000 --> 0:23:20.679 up and down the the the screen from the source. 0:23:21.600 --> 0:23:25.520 So that's one of the things that c c D 0:23:25.760 --> 0:23:31.560 image sensors can fall victim to, but not CMOS. And 0:23:31.680 --> 0:23:35.480 it's all because that global shutter exposes that image, the 0:23:35.880 --> 0:23:41.600 whole image simultaneously, and it's all gathering that light. And 0:23:41.920 --> 0:23:47.679 once the predetermined shutter speed for that global shutter has elapsed, 0:23:47.920 --> 0:23:52.080 it stops gathering light, turns that that entire exposure into 0:23:52.160 --> 0:23:57.320 an electronic image, and then starts again. And the rolling 0:23:57.320 --> 0:24:01.720 shutter just doesn't have that aim effects, so the smear 0:24:01.800 --> 0:24:06.800 does not happen with that, and it's you know, it's 0:24:06.880 --> 0:24:11.359 very noticeable. If you see the the effects of this, 0:24:11.480 --> 0:24:15.320 you'd think, oh, well, that's unfortunate that there's this weird 0:24:15.880 --> 0:24:20.040