The author of the material is Daniel Oziębała.
Exposure on lossy recording
In automatic mode, the smartphone is responsible for setting exposure as well as data processing. This does not mean that the user's role is limited to pressing the virtual shutter button. Currently, photo applications offer many options, and among them is exposure control. This is a very useful option that will save more than one photo, regardless of the season.
In most applications, the exposure setting is associated with the choice of focus point and is triggered by touching any part of the photo with your finger.
In the case of the default application from Apple (but also from various manufacturers of Android smartphones), after touching a given place in the photo a square and a slider appear on the screen. The first one indicates the subject on which the camera will focus. In turn, the slider with the sun allows you to control the exposure. Unfortunately, this is a very imperfect and imprecise way to control parameters, because the eyes and image visible on the screen are not trustworthy. The reason is simple – looking at the screen it is difficult to determine whether the photo is exposed correctly, underexposed or overexposed. Third party applications come with help, and with them … (continued under "Histogram, WaveForm, Live Analysis")
RAW recording is the preferred method of recording by photographers using SLR and non-DSLRs, in the case of smartphones it is used less often, and it is worth it because it allows full control and at the same time obtaining much better results than what automatic mode provides.
The selection of sensitivity (ISO) and shutter speed allows not only to expose the photo sufficiently, but also to achieve artistic effects that are hard to achieve in an automatic machine.
Water that looks like milk, a stream that seems to be moving, freezing time so that you can see each droplet is just a very narrow range of effects that can be achieved by choosing the right exposure time.
Author: Maxence Boyer Photo
You do not need to take -15 or even -30 shots of the same object in search of the right setting. Graphics and services for professional photographers and photography enthusiasts who want to share their work come to our aid. Some of them allow you to view not only the equipment, but also the settings that were used to take the photo. It is worth, however, to correct the fact that smartphone limitations will often make it impossible to achieve a similar effect without very severe overexposure or underexposure of the photo. However, knowledge of your equipment is often useful, along with useful ISO values.
ISO is a very important parameter that defines pixel sensitivity. The higher the sensitivity, the more information the matrix will capture. However, this has consequences in the form of noise. The effect of noise on the picture can be seen in the picture above. The lower the value, the richer the detail is. As the sensitivity increases, the image loses clarity and becomes less useful. The values of useful ISO for smartphones are much lower than for APS-C or Full Frame cameras – in the case of iPhones, values above ISO 200 can cause visible degradation of photo dynamics, as well as a significant increase in noise.
Several tools are useful in getting the image properly exposed …
Histogram, Waveform, Live analysis
– histogram – it can take various forms, but usually it has the form of a graph inside a rectangular frame. The frame has boundaries both horizontally and vertically. Exceeding them means irrevocable loss of data.
- The left part of the graph shows information about the shadows, i.e. the darker parts of the photo
- The right part concerns lights, i.e. bright parts
- The height of the graph indicates the number of points of a given brightness in the photo
- The situation when part of the graph goes beyond the histogram is the so-called "clipping"
When the graph visibly exceeds the borders of the left side of the histogram, black spots will be visible in the photo and further processing will be useless.
A similar situation occurs when the graph exceeds the right border and white spots will be visible in the photo.
The height of the graph indicates how much of the image is a specific portion of the light or shadow. The histogram for a correctly set exposure may look like this –
However, this is not the rule and its appearance may vary depending on the conditions. Often there are situations in which there is a strong contrast between light and dark parts of the image. The histogram in such situations may have not one distinctive hump, but two.
Depending on the settings selected, the histogram may show only light and shadow, and may also include three colors – red, green, blue – whose interpretation does not differ much from what we just discussed.
However, the histogram has its disadvantages, and one of the most severe is the fact that it does not indicate exactly which places are overexposed or underexposed.
– Waveform – displays information inside a rectangular frame, but uses waves instead of bars. These waves form an image representing what is visible on the screen, making it very easy to see exactly where the clipping occurs.
Waveform ranges from 0 to 100. A value of 0 means true black and 100 is true white. Both values are synonymous with clipping, because they are in vain to look for any details. Therefore, when choosing exposure parameters, we try to keep the wave between 0-100, although very often it will not be possible to achieve.
It goes hand in hand with waveform wektroskop. It has the shape of a circle inside which colors are displayed. Looking at them, it's easy to see what color dominates the picture.
Live Analytics (Live Analytics)
Live Analytics is a solution that in the context of smartphones is primarily associated with the FiLMiC Pro and FiLMic Firstlight applications. Live analysis displays the places where information is lost directly in the image and in my opinion it is the most convenient and the most useful tool among the three mentioned. Especially since the live analysis goes hand in hand with the histogram on the right.
The last step is to press the virtual shutter and possible editing in the program or application intended for it. It can be Lightroom, Snapseed, RNI Films, RawTherapee or something else.
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