BS ISO 19084 2015 pdf download – Photography — Digital cameras — Chromatic displacement measurements.
3.4 Image/camera settings The camera should be set for auto-exposure and the mean digital value in the image shall be reported. If exposure adjustment is available, exposure should be adjusted to give a mean value of the whole chart between 110 and 160. The mean value is calculated on the output image including black pattern and white background. The image should not be clipped in either bright or dark parts of the chart. White balance should be adjusted to render the centre of the image as neutral as possible. The focusing shall be such that the centre of the image is in focus. Chromatic displacement is strongly affected by camera settings, such as the f-number, the focal length, and the distance to the object, and these settings should be set preferentially to their factory shipping values. Depending on the purpose of the measurement, the camera settings, such as ISO sensitivity and other image settings, may be adjusted in the following manner: ISO sensitivity and exposure time may be adjusted so that no visible noise or no banding caused by light source flicker is observed in image. The aperture number and focal length shall be reported along with the ISO sensitivity and the exposure time. More precisely, the ISO sensitivity of the camera may be set to the minimum so as to minimize noise. The user settings such as colour and contrast may be deactivated. If possible, compression and sharpness should be set to their minimum values. If colour encoding is not sRGB, for example opRGB, it shall be reported. 4 Analytical approach 4.1 General As the first step for each of the test chart objects the horizontal and vertical distances between the green and the red channel (ΔR H_i , ΔR V_i ) and the green and the blue channel (ΔB H_i , ΔB V_i ) need to be determined (see Figure 7).