What Is Monitor Colour Calibration? How Does It Affect Photographers?

We all know that under “ideal” conditions, the colours of a photo should be exhibited consistently regardless of the devices used (monitor, printer and mobile devices, etc.); but unfortunately, this is never the case. The colours of the same piece of work could appear very differently on the computer monitors at the office, home and customer terminal; this indeed is very troublesome to many photographers. What we need to do at times like this is to conduct colour management. So what exactly is colour management? In simple terms, it utilizes controllable colour conversion technology so that the colours displayed on various devices can be reproduced “as closely as possible”. The reason why each device exhibits colours differently is not only due to the colour modes used on each device are different, but also caused by minor differences in the batch components used for mass production. How to resolve the problem like this? Now, what we need is a standard colour space to be acting like a trading market to allow two different devices to convert colour spaces or colour gamuts accordingly; hence, we can see colours been reproduced as closely as possible on different devices.

Under “ideal” conditions, consistent colours should be able to be reproduced for the same image on different devices. 

So who defines the standard colour space? The answer is the International Colour Consortium (ICC), and the standard colour space is called PCS (Profile Connection Space). Besides the standard colour space, ICC also defines the ICC profile. ICC profile is associate with the current status of each device, for example, an .icc or .icm file is generated after performing colour calibration for a monitor. The ICC profile defines the colour characteristics of the associated device, and the method to perform conversion to the standard colour space. Using PCS as the “trading market” to help colour gamut conversion between devices (such as: Adobe RGB→L*A*B*→CMYK), and together with the characteristics described in the ICC profile, photographers can easily reproduce consistent colours on different devices.

Through ICC profiles, devices can perform conversion to the standard colour space to exhibit consistent colours.

Generally speaking, in order to conduct colour management, it must be implemented from the capture end all the way to the output end. For a photographer, not only does the same colour gamut (such as: Adobe RGB) needs to be selected for the camera, photo editing software (such as: Adobe Lightroom/Photoshop) and monitor, colour calibration must also be performed on each computer monitor and output device that they work on. This will ensure the colours of the photos are the most accurate when photographers or photo editors are working or submitting their works. Monitors, printers, scanners and other devices should all have their unique ICC profiles. Take the monitor that been used by photographers daily for example; this ICC profile will be generated after the monitor is calibrated by a calibrator. After the images are edited using post-production software, this ICC profile must be embedded into the image when saving the file in order to ensure that the most accurate colours are displayed when output on other monitors or printers.

Of course, completing the steps described above alone is not enough to ensure an accurate colour representation because the right colour space needed to be selected in the photo editing software (such as: Adobe Lightroom/Photoshop) in order for the photographers to see the most accurate colours. So how can ICC profiles be used correctly in the software to confuct colour management? You could find these information in the following article.

Further reading: How is ICC Profile Used in Photographer’s Workflow?

Before explaining 3D-LUT, let’s first understand what LUT is. The full name of LUT is Look-Up Table. Its main function is to interpret the colour signal from the computer, find the corresponding output value in the Look Up Table, and then display the result on the monitor. We all know that an image is composed of many dots (pixels), and the information (bit depth) recorded in each pixel consists of colour information. In the monitor world, LUT is used as an index. The corresponding new values are found from LUT and then displayed. The advantage of this is that it can display the colours more efficiently. The biggest difference between 3D-LUT and traditional 1D-LUT is that the latter finds the corresponding colour values (R, G, B) in three one-dimensional Look-Up Tables of R, G and B individually, and the index source of 3D-LUT is a three-dimensional colour combination chart, and corresponding values are found from within. Its greatest advantage is that it can display the correct colours more accurately.

Compared to 1D-LUT, 3D-LUT has a three-dimensional color combination Look Up Table concept, able to interpret the in-between color values even more accurately, and allows the monitor to display a much more continuous tone transition.

1. Turn on the monitor for a period of time to warmup (approximately 30 minutes).
2. Open the colour management software and colourimeter or spectrophotometer, and follow the instructions from the software to perform colour calibration.
3. After completing all the colour calibration steps, the colour management software will analyze the measured data and save related information in the LUT of the monitor, and save the related ICC file in the system OS. 
4. Afterwards, every time the system turns on, it will automatically apply the ICC profile to match the LUT output of the monitor.

More knowledge on monitor hardware colour calibration: 

Art Suwansang’s Video Review of SW320: Hardware Calibrated 4K Display for Photographers

BenQ SW2700PT is the Best Monitor for Hardware Calibration for professional Photographers

Portrait Photographer Piotr Piatek Demonstrates how to Hardware Calibrate Photographer Monitor SW271