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Introduction to the ColorChecker test card
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ColorChecker test card, including six gray color blocks, plus three primary colors (red, green, blue), subtractive three primary colors (yellow, goods, green), and color and simulation of natural objects, the real color, Block, from left to right and then from top to bottom, respectively, labeled 1-24. So called 24 color card. For the camera color and white balance test, we used the ColorChecker test card in different environments using the corresponding white balance mode shooting comparison, on the one hand can observe the model of the various colors of the reduction, on the other hand you can observe them Of the white balance accuracy.
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ColorChecker test card application area
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Digital camera: check the camera, lens and optical system color reproduction, digital camera image color correction, contrast test target white balance, in the color reproduction system to reproduce the true color.
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Video: Check the camera to reproduce the quality of static and dynamic colors, check the color reproduction of the camera and its optical system, and restore the color of the projection system.
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Electronics Industry: Detects color reproduction of scanners, monitors, and monitors.
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Printing industry: to detect any printing and proofing procedures, detection of film, light, filters and paper.
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Use the ColorChecker test card
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(1) color reproduction
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The Colorchecker test card can actually restore colors in any light. The first time you want to shoot should be ColorChecker standard color card, the specific steps are as follows:
ColorChecker測試卡簡介
ColorChecker測試卡,包含六級灰度色塊,加色三原色(紅、綠、藍),減 色三原色(黃、品、青),以及膚色和模擬自然物體的真實色彩, 標板有24個純色塊,從左到右再從上到下,分別標記為1-24。所以又叫24色卡。 對于攝像頭色彩與白平衡的測試, 我們采用了ColorChecker測試卡在不同的環境下使用相應的白平衡模式拍攝進行比較,一方面可以觀察機型對各種色彩的還原情況, 另一方面可以觀察他們的白平衡準確度。
ColorChecker測試卡應用領域
數碼相機:檢查相機、鏡頭及光學系統的色彩還原情況,數碼相機的圖像色彩校正,對比測試目標白平衡,在色彩還原系統中再現真實色彩。
影像視頻:檢查攝像機靜態與動態彩色的重現質量,檢查攝像機及其光學系統的色彩還原情況和放映系統的色彩還原等。
電子行業:檢測掃描儀、顯示器、監視器的色彩還原。
印刷行業:檢測任何印刷和打樣程序、檢測菲林、光線、濾色片和紙張。
ColorChecker測試卡使用方法
(1)色彩還原
Colorchecker測試卡可以在任意光照下真實的還原色彩。您第一個要拍攝的應是ColorChecker標準色卡,具體步驟如下介紹:
1、把ColorChecker測試卡放在拍照現場(不需要填滿取景器)
2、保證相機能拍到所有色塊
3、讓ColorChecker測試卡位于構圖中有代表性的部分,不要處于陰影中或者曝光過度的高光位置
4、不要讓別的物體反射的光線投射到色卡上
5、拍攝帶有色卡的照片
6、在Photoshop中被打開時,會有一個內置的參照點
7、用取色器對黑色塊取樣。RGB之間的差值應該在7各單位內,約為245
8、對白色塊取樣。 RGB的值約為245
9、檢查色偏。選擇中間的灰色色塊,RGB的值約為128,相互之間的差值也不應超過7
10、如果讀數十分偏離,應用水平或曲線調回上述狀態
11、保存設定。該設定可用于同一光照條件下的其他圖形。
12、進一步的視覺色彩匹配可用其余色塊進行。
注意: 應使用經過校正的顯示器,并且實物ColorChecker測試卡應置于可控制照明條件的標準光源下
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(2)配合PM5等專業軟件可以生成數碼相機自定義的ICC文件
1、在自然跟可控制光線下拍攝色卡的時候,注意調整好適當的角度,不要讓讓光線直接通過色卡反射到鏡頭當中,也不要讓其他物體反射的顏色投到色卡上,這樣有可能造成比較大的偏差,并且讓PM5在計算icc的時候出現較大的錯誤;
2、盡可能采用手動精確白平衡進行白平衡的鎖定,可以采用灰平衡卡、白平衡卡等等。
3、曝光要控制好,可以打開直方圖觀察,并調整曝光補償,注意讓白色塊的色值達到210-245之間方為理想。而對于黑色塊的要求,可以不必理會,因為對于寬容度比較大的機型來說,當白色塊達到210-245的量度的時候,黑色塊已經不太可能小于23了,反而對于寬容度較小的機子卻容易做到。而這里的意義實際上是盡可能控制好曝光,讓色卡中的色塊達到理想的白點和黑點。
4、拍攝的時候把機內所有關于對比度及色彩的設置全部設為默認值,并且也注意不要設置銳化的選項,這樣也會對拍攝出來的色卡的顏色產生影響。
5.要盡量保證色卡表面的光線均勻分布,不要出現半明半暗的情況,推薦最好使用雙光源,分別從左右以45°入射照亮色卡。
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1, the ColorChecker test card on the camera scene (do not need to fill the viewfinder)
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2, to ensure that the camera can take all the color blocks
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3, so that the ColorChecker test card is located in the composition of the representative part, not in the shadows or excessive exposure to the high light position
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4, do not let other objects reflect the light projected on the color card
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5, take a photo with a color card
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6, in Photoshop is opened, there will be a built-in reference point
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7, with the color of the black block sampling. The difference between RGB should be about 7 in 7 units
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8, the white block sampling. The value of RGB is about 245
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9, check the color shift. Select the middle of the gray color block, RGB value is about 128, the difference between each other should not exceed 7
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10, if the reading is very deviated, the application level or curve back to the above state
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11, save the settings. This setting can be used for other graphics under the same lighting conditions.
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12, further visual color matching can be done with the remaining patches.
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Note: The calibrated display should be used and the physical ColorChecker test card should be placed under a standard light source that can control lighting conditions
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(2) with PM5 and other professional software can generate digital camera custom ICC file
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1, in the natural control of light with the color card, pay attention to adjust the appropriate angle, do not let the light directly through the color card reflected to the lens, do not let other objects reflect the color cast on the color card, so There may be a relatively large deviation, and let PM5 in the calculation of icc when there is a big mistake;
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2, as far as possible using manual precision white balance for white balance lock, you can use gray balance card, white balance card and so on.
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3, the exposure to control, you can open the histogram observation, and adjust the exposure compensation, pay attention to the color of the white block to reach 210-245 between the ideal side. And for the black block requirements, you can not ignore, because for the relatively large tolerance models, when the white block to reach the measure of 210-245 when the black block is less likely to be less than 23, but for the tolerance Small machine is easy to do. And the meaning here is actually as much as possible to control the exposure, so that the color card in the color block to achieve the ideal white and black spots.
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4, when shooting all the settings on the contrast and color settings are all set to the default value, and also do not set the sharpening option, this will also be shot out of the color card color impact.
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5. To try to ensure that the color of the surface of the card evenly distributed, do not appear half-dark situation, it is recommended to use the best dual light source, respectively, from about 45 ° incident light color card.
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