Understand histograms, so that you achieve the perfect exposure.

With a digital camera (hereinafter referred to as DC) image processing technology continues to evolve, more and more in-camera histogram function. .Although the histogram for beginners, very strange. .But it already exists in our life and work. .Such as in the famous Photoshop image processing software inside histograms corresponding to the command is Histogram (Chinese version of the "straight party <p> with a digital camera (hereinafter referred to as DC) image processing technology continues to evolve, more and more in-camera .the histogram function. Although the histogram for beginners, very strange. but it already exists in our life and work. as in the famous Photoshop image processing software inside histograms corresponding to the command is Histogram ( .Chinese version of the "histogram ")。</ p> <p> the meaning of the histogram in the histogram of an image, the horizontal axis represents the brightness of the image, from left to right, from the black gradually .transition to full white; vertical axis is represented by the brightness of the image in the range of the relative number of pixels. Zhanger Wei in such a coordinate system, we have a picture of light and shade can have an accurate understanding of the degree. In Photoshop .in, click "Image → Adjustments → Levels (shortcut: Ctrl + L)" to open the Levels adjustment box, adjust the image histogram, thereby controlling the image brightness changes. < ./ p> <p align="center"> Figure 1 Histogram Legend </ p> <p> histogram features </ p> <p> DC in the histogram function of Photoshop in the same. When the straight side .Figure in black color preference for the left, indicating the overall tone dim picture, pictures can also be understood as less exposed. And when the black color concentrate on the right, indicating the overall tone of the picture brighter side, except .special composition needs, or we can be understood as overexposed photos. Here, we use a few photos to intuitively understand the characteristics of the image reflected in the histogram. </ p> <p align="center"> Figure 2 exposure accuracy < ./ p> <p> Figure 2 is a normal exposure photographs of buildings and their corresponding histogram. we can see, the more left in the position of the histogram, the peak is relatively high and relatively dense, it is because construction .matter back to have more dark areas, while the histogram is reflected in the position of the left side of the distribution of dark areas. In the central-right position of the histogram, we can also see a higher peak, which is .because the large image area corresponding to the yellow light is here. In the far right of the histogram, we can see a small and prominent peaks, corresponding to the image, building on behalf of the cylinder is the strong reflection, .Since the luminance is too large, beyond the scope of the histogram can say, so it is reflected in the right form a peak. </ p> <p> expressed according to the contents of the histogram, the brightness of the picture in its basic .best performance within, and not many of the overflow section. more critical is that this picture brightness of each object is in line with our general understanding, that this picture is more accurate exposure .. </ p> <p align="center"> Figure 3 Figure 4 overexposure underexposure </ p> <p> in the same circumstances, if we take the time to increase or decrease the exposure, it will respectively .are shown in Figure 3 and Figure 4 results. in Figures 3 and 4, we can see clearly. If the increased exposure, then the histogram on the left part of the performance of shadow almost a blank. and if the reduction of exposure ., then the histogram can see the opposite result. Thus, if we see a histogram, if you do not see the image, its brightness can have an accurate understanding of the degree. </ p> <p .> It should be noted that the histogram peak is not centered and the image is relatively uniform exposure of the right to determine the accuracy of the exposure of an image, the key is to see if it accurately reflects the intent of the photographer. such as the usual .Night pictures, in the histogram peak area is mostly dark. </ p> <p> to Figure 5, for example, the histogram is concentrated in the large black area on the left shows the image of the shadow part of the lot, which also .consistent with the general concept of the people on the night. There is also a smaller peak in the histogram of the right, corresponding to the image is due to highlight some of the light. Although the graph in this histogram is not evenly distributed in the central .position, but due to the special scene shooting, and therefore an example of the correct exposure. This situation is relatively rare in everyday life photos, but I believe for us to understand the concept of the histogram will be very helpful. </ p> < .p align = "center"> Figure 5 night light </ p> <p> actual histogram </ p> <p> histogram in understanding the basic concepts of information and expression, we how to apply relevant knowledge .photo shooting day go? After all, DC's EVF viewfinder LCD viewfinder and LCD screen, all by itself, brightness, color saturation, sharpness and other display characteristics, and limitations on the image and the actual performance will always be certain .differences, a direct impact on our picture brightness level (exposure) accuracy of judgments and choices. The appearance of the histogram, then just add this point less. </ p> <p> Specifically, the histogram of the DC .The application can be divided into two aspects: one is to check the images after shooting the exposure situation; the other hand, is the photographer pressing the shutter before shooting to provide an accurate picture of light and shade reference, the photographer can be based on actual .need to adjust the exposure parameters to ensure the accuracy of the exposure of photos. </ p> <p> then we will explain how to shoot specifically in the more rational use of this feature histograms to obtain accurate exposure photography. .1. how to use histogram </ p> <p> most current mainstream with the histogram function of the camera, the Sony F828 digital camera as an example. the aircraft before shooting, according to the different viewfinder, the camera's LCD viewfinder screen .can instantly display the corresponding histogram information (see Figure 6). If the current information overload dark histogram shows the image underexposed, the photographer can appropriately increase the exposure, so that the whole curve of the histogram to the right translation, .to get the right exposure. may be subject to change based on the histogram, to determine whether exposure has been adjusted to the appropriate parameters. and vice versa. </ p> <p align="center"> </ p> <p align = " .center "> Figure 6 shows the histogram framing </ p> <p> this way, we can understand the camera built-in histogram function will be to get the size of the picture's exposure, then, how to further adjust the color so you can see .distribution histogram order it? </ p> <p> 2. exposure adjustment </ p> <p> in order to get proper exposure of photographs, we can use various methods to change the exposure parameters, until the histogram .histogram shows the image taken to achieve our goal. The following will give you three examples to demonstrate how to use a different technology to accurately capture the purpose of exposure (Note: In order to more clearly show the histogram, this example will use Photoshop .indicated in the histogram). </ p> <p> Method One: Using the exposure compensation function, direct adjustment of exposure </ p> <p align="center"> Figure 7 underexposed </ p> <p> .Figure 7 is a bustling night market in Hong Kong, Causeway Bay, lighting, signs the whole picture in various light boxes, neon-based. histogram peaks of the two curves on both sides and were concentrated in the overflow, which shows photos of the light and dark contrast is too high, bright screen .Department of dark detail screen will have irreversible damage. By analyzing the situation, it is easy to see that many features are "hidden" in the histogram of the dark area, did not get the performance. </ p> .moderate exposure <p align="center"> Figure 8 </ p> <p> At this point, we passed an increase from 0.3 to 0.7 exposure compensation (+ EV) results can be obtained in Figure 8. you can see, just darkness .The scene has a lot more detail, the performance of the entire image is relatively close to the feeling of the naked eye. </ p> <p> this point, if additional 0.3 to 0.7 exposure compensation (+ EV), it will be like .Figure 9 this effect: the image brighter, but were dark noise increased significantly, the whole picture has no night the atmosphere was. Therefore, if, as in Figure 9 such exposure, shadow detail can indeed be very good expression, but highlights .been exposed too much, but image quality is not good, this is the truth too far. Therefore, if we see a histogram such as shown in Figure 9, caused by overexposure serious loss of highlight details of the problem, it can reduce .0.3 to 0.7 exposure compensation (-EV) to fix, to get the results in Figure 8. </ p> <p align="center"> Figure 9 Exposure transition </ p> <p> that many cameras offer .similar exposure compensation function keys, and if not, the camera can also be found in the option menu. </ p> <p> Method Two: flexible use of metering mode </ p> <p> camera exposure .is its built-in metering program in determining the brightness data, combined with the data inside the calculated exposure. In normal circumstances, the default metering programs are center-weighted metering, most of this metering mode .case, it can get the right exposure parameters. but there are exceptions, then, we can use the camera's spot metering function, and for the brightness of the neutral gray (similar to the middle of light and dark areas) regional test .light conditions are most suitable to meet the exposure parameters. A similar method also has multi-spot metering metering, etc., according to the specific function of the camera, combined with experience to apply them. </ p> <p> Method Three: Direct .adjust the exposure parameters </ p> <p> even experienced photographers can histogram data, roughly estimate the amount of exposure should be compensated, manual on the aperture, shutter and other exposure parameters to adjust. not only get the right .exposure, but also according to the actual situation, combined with depth of field, exposure rate is more reasonable to consider are the exposure parameters. </ p> <p> change the way a lot of exposure, but no matter what method used, the key is .To understand the meaning of the histogram, before shooting to ensure the results of their own be aware of the shooting, which captured the image histogram and reasonable. </ p> <p> 3. use the real meaning of the histogram </ p .> <p> reference histogram information to determine the true meaning of the exposure parameter is a direct images of the inside information, to obtain the most suitable exposure parameters will not be EVF or the LCD display and the actual image itself, the exposure differences. As .image-related physical characteristics of input and output devices are inconsistent, especially in the home environment, the more difficult to get a strict sense of the unity of the color description, which is caused by us after the shooting and the shooting view, print is not seen from .reasons, and the surface of the image histogram performance aside, the real and reliable data to give us a quantifiable standard for the latter part of output. Therefore, in order to be a small a level of photography enthusiasts, on the histogram .understanding is essential. </ p> <p> Related Links: * how to shoot water features color photography basics corrugated real mystery behind the reduction of the realism of photography (I) * Sweet Valentine .section teaches you how to shoot heart-shaped lights macro photography skills and experience to restore the real behind the realism of photography (in) * master moves to teach you how to clear away obstacles to run out of buckwheat Faulkner .Lee classic portrait shot to decrypt a large landscape photography of the 11 Fun Dafa how to shoot beautiful people do not look artificial </ p>.