Real-time tone mapping method based on cumulative histogram

Abstract

The invention discloses a real-time tone mapping method based on an accumulative histogram. The method comprises the following steps: carrying out histogram smoothing processing to obtain a smoothed histogram; setting a brightness offset coefficient and a contrast factor to adjust the smoothed histogram; calculating a cumulative histogram according to the adjusted smoothed histogram; performing transformation through the cumulative histogram to obtain a global mapping curve; a unique histogram smoothing algorithm is adopted, the histogram is effectively processed in all dimensions, the histogram is protected to be processed in the horizontal direction and the vertical direction, the wide dynamic effect is achieved without depending on a single frame of a multi-frame image, the overall occupied calculation amount is extremely low, the real-time performance is achieved while the wide dynamic effect is guaranteed, and the real-time performance is achieved. And the smoothing algorithm does not use a complex calculation process and excessive parameters, so that resources are greatly saved, and the operation efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of image processing, in particular to a real-time tone mapping method based on cumulative histograms. Background technique [0002] The tone-mapping function is an enhancement technique that optimizes an image by attempting to represent a high-dynamic-range input image with a low-dynamic-range output image; the goal of tone-mapping is to preserve the local contrast and Details, while maintaining the overall balance of the picture and the structure of the image in the output image; tone mapping is a computer graphics and imaging technology that approximates a high dynamic range image on a limited dynamic range medium; printers, monitors, and projectors have only Limited dynamic range; in essence, the problem to be solved by tone mapping is to perform a large contrast attenuation to transform the brightness of the scene to a displayable range, while maintaining image details and colors, which are very importan...

AI Technical Summary

Problems solved by technology

Cannot make adaptive adjustments based on scene information, resulting in the algorithm not being able to adapt to most scenes;

[0010] 2 Local tone mapping, the local tone mapping process consists of applying a set of global mapping curve weights to each local tone mapped pixel value in the frame; the mapping transfer curve is specified as a set of point values, with points in between using The linear interpolation is derived; the transfer curve of each segment of the local is obtained by analyzing each segment of the pixel after the global mapping process; the local tone mapping is not applied in the bypass mode; the local tone mapping algorithm is obtained by analyzing the whole of the source image Pixels and local pixels, so self-applicability is strong; but the algorithm process is complicated and cannot achieve real-time performance

[0015] 3. The effect of the global algorithm is generally inferior to the local method

[0021] 1. Pixels with the same color before mapping may have different colors after mapping;

[0022] 2. The local algorithm is generally more complex than the global method, and the speed is relatively slow;

[0024] 4. Phenomena such as halos will appear

[0025] Nowadays, the research hotspots of tone mapping methods mainly focus on the innovation of local methods, and there is no improved tone mapping method based on global methods.

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