CN104486603A - Multi-projection color correcting method based on HDR (high dynamic range) imaging - Google Patents
Multi-projection color correcting method based on HDR (high dynamic range) imaging Download PDFInfo
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- CN104486603A CN104486603A CN201410669501.9A CN201410669501A CN104486603A CN 104486603 A CN104486603 A CN 104486603A CN 201410669501 A CN201410669501 A CN 201410669501A CN 104486603 A CN104486603 A CN 104486603A
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Abstract
The invention provides a multi-projection color correcting method based on HDR (high dynamic range) imaging. According to the method, a commercial camera is used for carrying out color correction on a system, and the camera becomes feedback equipment in the system through recovering curves corresponding to brightness of each channel of the camera, and is used for recovering the curves corresponding to the brightness of each projector channel; then, a public color interval is built, and the colors of each projector are mapped into the interval; meanwhile, the self-adapting regulation is carried out on target images, the dynamic range of the system is enlarged as much as possible, the brightness correction precision of the system is ensured, and meanwhile, the image quality is improved. After correction, a plurality of projectors can project a complete unified image in a mutual cooperation way.
Description
Technical field
This technology belongs to projection tiled display technical field, is specifically related to the color correction technology of multi-projection system system.
Background technology
Along with people are to the progress of constantly lifting and engineering shadow casting technique that visual experience requires, multichannel shadow casting technique is widely used in fields such as large-scale activity, display and demonstration, the releases of new products.In multichannel optical projection system, because the situation such as overlap of the color distortion between different projector and view field causes the deviation of system interface in color, eliminate these deviations, allow multiple stage projector jointly show final goal that a complete unified image is multiprojector system.
Conventional method manually adjusts projector's Color Channel or adopts expensive optical instrument to correct to analyze the colors of means to system such as the output light of projector, and the former needs to consume a large amount of manpower, and the latter's complicated operation also improves system cost.
Summary of the invention
The invention provides a kind of many projected color bearing calibration based on HDR imaging, by carrying out self-adaptative adjustment to target image, improving the dynamic range of system as far as possible, while ensureing system brightness correction accuracy, improve image quality.
The present invention is achieved through the following technical solutions:
Based on many projected color bearing calibration of HDR imaging, comprise the following steps:
Step one, ask for the geometric maps relation between video camera and projector pixel according to different application scenarios, set up geometric maps table;
Step 2, allow projector's width that projects comprise the red image of 0-255 input value, taken by video camera, camera aperture is fixed, photographic images under different exposure;
Step 3, to the smoothing process of the photographic images described in step 2, get the central area of different brightness, ask its mean value, as the camera output valve corresponding to this brightness;
Each camera output valve calculated in step 4, use step 3, in conjunction with the time for exposure, solves the brightness response curve of camera red channel by optimal method;
Step 5, to solve the green brightness response curve with blue channel of camera according to the method for step 2-four;
The red channel of step 6, projector exports certain red value, and camera is chosen the suitable time for exposure and taken this image, progressively improves projector's brightness and photographic images;
Step 7, for the photographic images described in step 6, ask for the mean value in picture centre region, relative projection brightness is calculated by the time for exposure, after measuring brightness corresponding to all output valves, simulate a curve as projector's brightness response curve, make to use the same method and measure the brightness response curve of other passages of projector and other projectors;
Step 8, for each passage, choose the brightness range that a Ge Meitai projector can reach, as public brightness section, a color lookup table is set up for each projector Color Channel;
Step 9, for the overlapping region between neighboring projectors, calculate corresponding brightness decay weight masking-out according to the distance at pixel distance edge;
Step 10, target image to be mapped between public chromatic zones, geometric maps table, color lookup table and brightness decay weight masking-out are stored with graphics rendering pipeline, is adjusted the input value of each passage of projector by image real-time streams waterline in real time according to target image; The image now projected out will be the image that a width does not have geometry and misalignment.
Beneficial effect of the present invention:
The present invention proposes a kind of color calibration method based on HDR imaging, a commercial camera is used to carry out color correction to system, camera is allowed to become feedback device in system, for recovering the brightness response curve of each projector passage by the brightness response curve recovering camera each passage.Then set up between public chromatic zones, by the color map of each projector in this interval.Meanwhile, by carrying out self-adaptative adjustment to target image, improving the dynamic range of system as far as possible, while ensureing system brightness correction accuracy, improving image quality.After overcorrect, multiple stage projector can coact and project out in a complete unified picture.
Accompanying drawing explanation
Fig. 1 is the workflow diagram of the color correction that the present invention proposes.
Embodiment
The color continuity of the color correction technology primary responsibility process projected picture in many projections are seamless emerging system, for same color, can not have perceptible color to change during display.The color discontinuity considered is needed to be divided into color distortion between inner and projector of single projector equally in multi-projector display system, the colourity change of single projector inside can be ignored usually, but owing to being subject to the impact of camera lens vignetting and projector distance, brightness is dimmed gradually to surrounding by projection centre.Color distortion between multi-projector derives from projector's manufacture process and accurately cannot control colourity and brightness, and particularly, there is perceptible color distortion in the general commercial projector of cost relative moderate between the projector of same model.Overlapping region brightness between projector, apparently higher than other regions, is also the subject matter that we will solve in color correction process.
The present invention is made up of 4 basic modules in concrete enforcement, comprising:
(1) geometric correction module: for plane or almost plane, by projection gridiron pattern, acquisition homography matrix or bezier surface are to ask for geometric maps relation; For the curved surface that structure is relatively regular, by surface characteristics point matching bezier surface to ask for geometric maps relation; For the random surface of complex geometry, ask for geometric maps relation by structure light scan.
(2) camera response curve recovers module: by the pattern of the different brightness that projects, projection pattern is taken under different exposure time, calculate different brightness value, relation between exposure value and camera output valve by optimal method, recover the brightness response curve of each passage of camera.
(3) projector's response curve recovers module: use calibrated camera shooting to correspond to the projected image of different input value, calculate the brightness response curve of each passage of projector with this.In order to ensure measurement accuracy, shorten Measuring Time simultaneously, for each Color Channel of Mei Tai projector, projection 16 width image altogether, every width image comprises four brightness, get the region close to projection centre part, ask for region averages after level and smooth to calculate the relative brightness corresponding to this input value.
(4) the real-time mapping block of each Color Channel of projector: after obtaining the brightness response curve of projector, for each Color Channel, asks for a public color gamut, ensures that each projector can both export the brightness in this public region.After target image is carried out self-adaptative adjustment, target color values calculates input brightness in real time by the look-up table be stored in graphics rendering pipeline.
Multichannel projected color alignment technique based on HDR imaging comprises following step:
1, the geometric maps relation between video camera and projector pixel is asked for according to different application scenarios.
2, allow the red channel projection of projector from the image of 0-255 brightness.Taken by video camera, camera aperture is fixed, each shooting five images under different exposure.
3, to the smoothing process of photographic images, for the image under the same time for exposure, the center brightness of the identical luminance part of input is got.
4, in conjunction with the time for exposure, use equation below, solved the brightness response curve of camera red channel by optimal method, wherein Z represents camera output valve, and E represents the actual brightness value received of pixel cell, and t represents the time for exposure.
g(Z)
＝ln(E)+lnt
5, the brightness response curve of camera green and blue channel is solved according to the method for step 2-4.
6, the red channel of projector exports certain red value, and camera is chosen the suitable time for exposure and taken this image, and progressively improve projector's brightness and photographic images, each input value takes 5 width images.
7, get the value conduct of photographic images central area, calculate relative projection brightness by the time for exposure with camera output valve.After measuring brightness corresponding to all output valves, simulate a curve as projector's brightness response curve.Make to use the same method and measure the brightness response curve of other passages of projector and other projectors.
8, for each passage, choose the brightness range that a Ge Meitai projector can reach, as public brightness section, a look-up table is set up for each projector Color Channel.
9, for overlapping region, corresponding decaying weight masking-out is calculated according to the distance at pixel distance edge.Owing to asking for the brightness response curve of projector, decaying weight herein uses linear attenuation mode to calculate.
10, target image is mapped between public chromatic zones.Geometric maps table, color lookup table and edge decay masking-out is stored with graphics rendering pipeline.Adjusted the input value of each passage of projector in real time according to target image by the image real-time streams waterline designed.
Although with reference to preferred embodiment, present invention is described; but the above example does not form the restriction of scope; any amendment in spirit of the present invention and principle, equivalently to replace and improvement etc., all should be included in claims of the present invention.
Claims (3)
1., based on many projected color bearing calibration of HDR imaging, it is characterized in that, comprise the following steps:
Step one, ask for the geometric maps relation between video camera and projector pixel according to different application scenarios, set up geometric maps table;
Step 2, allow projector's width that projects comprise the red image of 0-255 input value, taken by video camera, camera aperture is fixed, photographic images under different exposure;
Step 3, to the smoothing process of the photographic images described in step 2, get the central area of different brightness, ask its mean value, as the camera output valve corresponding to this brightness;
Each camera output valve calculated in step 4, use step 3, in conjunction with the time for exposure, solves the brightness response curve of camera red channel by optimal method;
Step 5, to solve the green brightness response curve with blue channel of camera according to the method for step 2-four;
The red channel of step 6, projector exports certain red value, and camera is chosen the suitable time for exposure and taken this image, progressively improves projector's brightness and photographic images;
Step 7, for the photographic images described in step 6, ask for the mean value in picture centre region, relative projection brightness is calculated by the time for exposure, after measuring brightness corresponding to all output valves, simulate a curve as projector's brightness response curve, make to use the same method and measure the brightness response curve of other passages of projector and other projectors;
Step 8, for each passage, choose the brightness range that a Ge Meitai projector can reach, as public brightness section, a color lookup table is set up for each projector Color Channel;
Step 9, for the overlapping region between neighboring projectors, calculate corresponding brightness decay weight masking-out according to the distance at pixel distance edge;
Step 10, target image to be mapped between public chromatic zones, geometric maps table, color lookup table and brightness decay weight masking-out are stored with graphics rendering pipeline, is adjusted the input value of each passage of projector by image real-time streams waterline in real time according to target image; The image now projected out will be the image that a width does not have geometry and misalignment.
2. a kind of many projected color bearing calibration based on HDR imaging as claimed in claim 1, it is characterized in that, wherein solve camera output valve in step 4 and adopt following methods: wherein Z represents camera output valve, and E represents the actual brightness value received of pixel cell, and t represents the time for exposure
g(Z)＝ln(E)+lnt。
3. a kind of many projected color bearing calibration based on HDR imaging as claimed in claim 1 or 2, is characterized in that, wherein takes 5 width images during each photographic images.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106504200A (en) * | 2016-09-14 | 2017-03-15 | 上海方奥通信技术有限公司 | The image irradiation compensation method mapped based on hue shift estimation and pointwise tone and system |
| CN107438162A (en) * | 2017-07-31 | 2017-12-05 | 努比亚技术有限公司 | The method of adjustment and device of a kind of acquisition parameters |
| CN107925785A (en) * | 2015-08-24 | 2018-04-17 | 夏普株式会社 | Reception device, broadcast system, method of reseptance and program |
| CN108337493A (en) * | 2018-01-16 | 2018-07-27 | 长春华懋科技有限公司 | Automatic correction method of image color based on high-precision vision holder |
| CN110858877A (en) * | 2018-08-22 | 2020-03-03 | 杭州海康机器人技术有限公司 | Method and device for determining exposure time of projector |
| CN113079359A (en) * | 2020-01-03 | 2021-07-06 | 苏州佳世达光电有限公司 | Method for synchronously correcting colors of multiple projectors |
| CN117478802A (en) * | 2023-10-30 | 2024-01-30 | 神力视界(深圳)文化科技有限公司 | Image processing method and device and electronic equipment |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107925785A (en) * | 2015-08-24 | 2018-04-17 | 夏普株式会社 | Reception device, broadcast system, method of reseptance and program |
| CN107925785B (en) * | 2015-08-24 | 2020-07-07 | 夏普株式会社 | Receiving apparatus, broadcasting system, receiving method, and recording medium |
| CN106504200A (en) * | 2016-09-14 | 2017-03-15 | 上海方奥通信技术有限公司 | The image irradiation compensation method mapped based on hue shift estimation and pointwise tone and system |
| CN106504200B (en) * | 2016-09-14 | 2022-12-09 | 上海方奥通信技术有限公司 | Image illumination compensation method and system based on hue offset estimation and point-by-point hue mapping |
| CN107438162A (en) * | 2017-07-31 | 2017-12-05 | 努比亚技术有限公司 | The method of adjustment and device of a kind of acquisition parameters |
| CN108337493A (en) * | 2018-01-16 | 2018-07-27 | 长春华懋科技有限公司 | Automatic correction method of image color based on high-precision vision holder |
| CN110858877A (en) * | 2018-08-22 | 2020-03-03 | 杭州海康机器人技术有限公司 | Method and device for determining exposure time of projector |
| CN110858877B (en) * | 2018-08-22 | 2021-06-11 | 杭州海康机器人技术有限公司 | Method and device for determining exposure time of projector |
| CN113079359A (en) * | 2020-01-03 | 2021-07-06 | 苏州佳世达光电有限公司 | Method for synchronously correcting colors of multiple projectors |
| CN117478802A (en) * | 2023-10-30 | 2024-01-30 | 神力视界(深圳)文化科技有限公司 | Image processing method and device and electronic equipment |
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