Most raw converters, including Lightroom and Aperture, read the note and display large parts of your metadata but the only thing they use to influence their initial versions of your images is the white balance information. Everything else—including all the other secondary settings listed above—is ignored.
Even the white balance setting is used only for the initial rendering. In the case of white balance or contrast, it is almost guaranteed to affect every pixel, often in a way that might limit the changes you can cleanly make later. Although the secondary settings have no direct effect on the raw file, they do affect the histograms you see on the back of the camera.
As a photographer, you might use those histograms to change the exposure settings shutter speed, aperture, ISO that you choose, perhaps as a result of exposure compensation that you dial in.
This is why the first and second images above look so much darker than the third. In order for the numbers recorded within a digital camera to be shown as we perceive them, tone curves need to be applied see the tutorial on gamma correction for more on this topic. Color saturation and contrast may also be adjusted, depending on the setting within your camera.
The image is then sharpened to offset the softening caused by demosaicing, which is visible in the second image. The high bit depth RAW image is then converted into 8-bits per channel, and compressed into a JPEG based on the compression setting within your camera. Up until this step, RAW image information most likely resided within the digital camera's memory buffer.
There are several advantages to performing any of the above RAW conversion steps afterwards on a personal computer, as opposed to within a digital camera. Demosaicing is a very processor-intensive step, and so the best demosaicing algorithms require more processing power than is practical within today's digital cameras.
Performing the demosaicing step on a personal computer allows for the best algorithms since a PC has many times more processing power than a typical digital camera. Note the resolution advantage shown below:. Even so, a RAW file cannot achieve the ideal lines shown, because the process of demosaicing always introduces some softening to the image. Only sensors which capture all three colors at each pixel location could achieve the ideal image shown at the bottom such as Foveon-type sensors.
White balance is the process of removing unrealistic color casts, so that objects which appear white in person are rendered white in your photo. Color casts within JPEG images can often be removed in post-processing, but at the cost of bit depth and color gamut. This is because the white balance has effectively been set twice: once in RAW conversion and then again in post-processing.
To have less noise, you need to expose more, so you gather more light, which improves signal strength. A strong signal has a higher SNR, and thus appears less noisy. It should also be noted that if you are working with a scene that has high dynamic range, you may have some parts of your scene dark, possibly appearing overly dark on screen, whereas in real life those regions did not look as dark, as noisy, nor as devoid of detail.
This is where camera dynamic range plays a role. A camera with stops of DR will have more limited ability to have "shadow" detail pushed to restore realism, whereas a camera with stops will have an extended ability to have "shadow" detail pushed to restore realism.
The Nikon camera has less of both, significantly less read noise at low ISO , thus allowing shadow detail to be pushed more with less noise. Either way, these colors consist of Red, Green, and Blue values and by manipulating these values you can always adjust white balance or exposure, regardless of the file type In the real world, the color manipulation will sometimes lead to posterization or clipping if the source color precision was not good enough or the intended change was too extreme.
In digital images, light is just numbers, you can always increase numbers by adding or multiplying, unless there is not enough difference between numbers and even increasing these numbers won't yield different values for "dark" and "bright". More precision like in RAW files means more information about differences, means more room for "adding light". Most definitely not a stupid question: I actually wondered the same thing when I first got into shooting raw.
Before you can really understand what's happening when you adjust exposure in software, you first need to know what a digital camera's sensor and electronics do when you take a photo: count photons. Each pixel of the sensor essentially records the number of photons that strike it during exposure, and the raw file generated contains that data without modification plus some metadata, of course. Next, let's think about how this applies to a photo that's been underexposed by 1 f-stop.
By definition, 1 f-stop of underexposure means that the shutter was open half as long as it needed to be, that the aperture allowed only half the light through, or the ISO was set to half the sensitivity needed doesn't matter which , and all of these translate to one thing: the sensor only caught half the light needed for proper exposure.
Assuming the scene lighting isn't changing significantly from moment to moment, this also means that the photon counts read by the entire sensor are about half of what they need to be. Likewise, each subsequent f-stop of exposure above or below the intended exposure represents a doubling or halving of the photon counts.
To "add the light back", software uses this idea to estimate the correct number of photons counted for each pixel. This is done by multiplying each pixel by an appropriate correction factor, which is easily calculated. Unfortunately, though, the approach isn't always as wonderful as it sounds since any image noise in the photo is also scaled up by the same amount!
It's worth mentioning that this can be done with JPEGs, too, but it won't work as expected for a couple of reasons. Tags: advices answers experts guides learn photography questions tips.
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