It also means that color filter arrays can resolve differences in lightness far better than differences in color - with important implications for the diffraction limit. However, this human sensory trick isn't without trade-offs. The result is that green light contributes much more to our perception of luminance, and is also why color filter arrays are designed to capture twice as much green light as either of the other two colors. Our human visual system has adapted to be most sensitive to the green region of the light spectrum (since this is where our sun emits the most light - see the tutorial on human color perception). While these values will vary slightly based on the camera and RAW converter, they're a good rough estimate that's based on actual measurements. However, its extinction resolution is around ~2500 horizontal lines, so details as fine as 1.2-1.3X the pixel size may also appear. For example, Canon's EOS 5D camera has 2912 vertical pixels, but can only resolve ~2000 horizontal lines. Technical Notes: The real-world resolution limit of a Bayer array is typically around 1.5X as large as the individual pixels. Edges will also appear more sharp and defined. However, one could also argue that such features do indeed improve apparent image detail, which is often helpful with objects such as fine leaves or grass. One could make the argument that any detail finer than the artifact-free resolution limit isn't actually "real detail," and therefore shouldn't matter, since it's largely the result of the bayer array and digital artifacts. In the above diagram, the resolution limit would be past roughly the first two-thirds of the image. The artifact-free resolution is typically what one is referring to when they speak of the resolution limit. Beyond this resolution, detail may exhibit visible demosaicing artifacts, and may not be depicted in the same way it appears in-person. This describes the most closely spaced details which are still clearly distinguished from one another. In the above diagram, the extinction resolution will be near (or just beyond) the far right edge.Īrtifact-Free Resolution. Beyond this resolution, progressively finer detail will appear almost completely smooth. This describes the smallest features or edges that can be captured by your camera, although such detail may not necessarily be distinguished if it's too closely spaced, and such detail may also exhibit noticeable demosaicing artifacts. However, as with most things, it's not quite so clear cut.įor the purpose of this tutorial, two resolution definitions are relevant:Įxtinction Resolution. Once these lines can no longer be distinguished, the camera's resolution is said to have been surpassed. If it's not simply the pixel size, how does one define the resolution of a digital camera? Resolution is usually measured by taking a photo of progressively more closely spaced parallel lines. The exact resolution is really a matter of definition. The end result is that the camera's resolution is better than one would expect if each 2x2 block containing all three colors represented a pixel, but not quite as good as each individual pixel. While this can further reduce resolution, with recent digital cameras resolution isn't too severely impacted (compared to what's already lost from the color filter array). ![]() In front of the color filter array, most camera sensors also have another layer of material which aims to (i) minimize digital artifacts, such as aliasing and moiré, and to (ii) improve light-gathering ability. ![]() Using sophisticated demosaicing algorithms, full color information at each pixel is then estimated based on the values of adjacent pixels.Īnti-Aliasing Filter & Microlenses. Furthermore, the color array or "mosaic" is arranged so that green is captured at twice as many pixel locations than is red or blue. Most of today's digital cameras only capture one of the primary colors at each pixel: green, red or blue (as depicted to the left).
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