What does the HDR effect filter (post-processing filter) of Photoshop filter do?

Usually, an HDR image needs multiple images with different exposures to get it (are you tired of repeatedly adjusting EV? ), today I will introduce you to a very interesting and magical PS filter. Only one image is needed to obtain the HDR effect, and HDR is one of the latest and most advanced means to pursue the fidelity of the picture. So what is HDR? Simply put, HDR can be summarized in three sentences:

1. Bright places can be very bright.

2. Dark places will be very dark.

3. The details of the bright and dark parts are obvious, not light or dark.

HDRI is full of energy? Range? (HDR)？ The abbreviation of image was invented to solve this problem. Simply put, HDRI is an image with a very wide brightness range, which has more brightness data storage than other images, and its way of recording brightness is also different from traditional pictures. It does not compress the brightness information into the color space of 8bit or 16bit in a nonlinear way, but records the brightness information in a directly corresponding way, so it can be said that it records the illumination information in the picture environment. Many HDRI files are provided in the form of panorama, and we can also use it as the environmental background to produce reflection and refraction. It should be emphasized here that HDRI is fundamentally different from panorama. Panorama refers to an ordinary image containing a 360-degree scene, which can be in JPG format, BMP format, TGA format, etc. And it is low dynamic? Range? Light? Image, it has no lighting information.

What is the full name of HDR? Dynamic? Range means high dynamic range, such as so-called high dynamic range image (HDRI) or high dynamic range rendering (HDRR). Dynamic range refers to the relative ratio of the highest value to the lowest value of the signal. At present, the 16-bit integer format uses color values from "0" (black) to "1" (white), but does not allow so-called "out-of-range" values, such as color values at highlights where the metal surface is whiter than white.

With the help of HDR, we can use color values beyond the normal range, so we can render more realistic 3D scenes. Maybe we have all had this experience: driving through a dark tunnel, the exit is dazzling sunshine. Due to the huge contrast of brightness, we may suddenly lose sight of the things around us under white light. HDR can show its talents in such a scene.