Originally Posted by Kitteh5
Am I right to say higher the megapixel, the higher the quality? I've come to such a conclusion through my Droid's 5MP camera taking better pictures than my webcam, and my 12MP camera takes better pictures than both of those. The reason the Droid and the Webcam have worst quality than my Camera is merely due to their lower MP, correct? And if I was to take a picture with a 4MP camera (actual camera, not a phone) and compare it to the scene similarly shot with a 12MP camera, the 12MP camera would undeniably have higher quality?
Also, can anyone explain downsizing? What happens when I view a 12MP or even a 3MP camera on a 1080p monitor? If I had a source picture at 12MP, resized it to 6MP and then viewed both versions of the photo on a 1080p monitor, would the 12MP and the 6MP be different in anyway? Thank you for your time and any responses.
Nope, higher megapixels does not mean better quality photos.
Megapixels is a resolution count. A 12MP camera for example means the photo produced by the camera has a max resolution of 12,000,000 pixels.
Megapixels does not
indicate anything about quality. Rather, image quality (IQ) depends on the image sensor itself. Factors that impact IQ are sensor tech, sensor size (bigger physical sensor=better), and lenses. This is why a 5 year old DSLR with a 6MP sensor will give better photos than a brand new 14MP point and shoot.
Now as to your question of how come your phone has better photos: It's because of the sensor tech itself. As time goes on, sensor technology gets better. Sensors are refined so the images produced have less noise and are sharper. At the same time, companies try to cram more pixels into the sensor. So in the end, what you're seeing is a parallel evolution of both sensor technology and sensor resolution, and not a cause/effect relationship between the two.
However, sensor size matters a lot
with IQ. Your example above all use similar-sized sensors. If you were to compare sensors of different sizes, for example, you'd notice that the larger sensor almost always wins. Going back to a previous example, a five-year-old 6MP DSLR will beat a modern 14MP point and shoot because a DSLR has a much larger sensor than a point and shoot.
As for resizing, when you resize a photo, you throw away extra pixels. When you resize an 8MP photo to 4MP, for example, you're tossing 50% of the pixels. At first glance, the photos will look the same. However, if you were to print out both photos at a large size (say, 8"x10"), you'll notice that the 4MP photo will be a bit more pixelated than the 8MP image. That said, for uploading on the web, usually the extra pixels are irrelevent since standard web sizes are too small anyways to take advantage of the extra pixels.