Nowadays, newer digital camera tends to carry more and more pixels packed in the sensor. However, what can we really get from increasing number of pixels? Will the image be sharper? Is there any undesired side effect?
Pixel Count of Image Sensor
Pixel count of an image sensor is often referred as “the resolution”. Many people believe that the camera can resolve more detail if the pixel count is higher. They also believe that additional image detail brings better sharpness. This is entirely wrong. Theoretically, the true resolution is always bound to the Nyquist frequency of the digital sampling density. However, in reality, there are other bottlenecks influencing the power to resolve image detail.
True Optical Resolution
True optical resolution refers to the real and measurable performance of the power to resolve the image detail. Typically speaking, we can use the ISO 12233. Through taking photo of the chart, we can measure the true optical resolution of the camera.
Sharpness may correlate to resolution, but the true relationship between sharpness and resolution is different from what most people think. To be more precise, sharpness is actually associated to contrast around the image detail.