Colour management in the photo lab

Colour management in the lab allows a printing device to accurately convert the src="Images color space to the colour space of the printer, maintaining the colours of the original scene as close as possible.

ICC Profiles

Icc profiles are embedded in image files describing the colour space of that image. This is the colour space of the input device(camera).

Icc profiles also describe the colour space of the output device (printer).

Image colour spaces

Up until recent years, src="Images were encoded in sRGB color space. Recently wider gamut spaces have been used, such as Apple using Display P3 profile space, on their devices. Android has also adopted wider colour spaces, available by a setting.

Printer colour spaces

Silver halide printer's colour space approximated sRGB colour space, within the limitations of the technology. Ink-jet printers expanded the available gamut to well exceed sRGB space. Epson, Noritsu and Fuji ink-jet minilab printers closely match AdobeRGB space.

Silver halide printer technology matched the colour space of film, without the use of icc profiles. Early digital technology, camera and printer, standardized on sRGB colour spaces. So we didn't need to be too concerned about color management. Now, with new input colour spaces adopted, we need to get involved.

Gamut

It is important to understand that "wide-gamut" matters most for output devices such as printers and displays: They can print or display more colours. Wide-gamut input devices(cameras) map their colours into a larger space, possibly including more colours and detail.

Profile conversion

The printer software converts the image, using the image's embedded profile, into the printer's colour space. If the image has no embedded profile, the software makes an assumption, usually sRGB, or by a default software profile setting.

• If the input device's colour space is larger than the output device; the out-of-gamut colours need to be mapped into the smaller output space.
• If the input device's colour space is smaller than the output device; the colours are mapped directly into the larger output space.

Profile mismatches

If the printer mismatches the profiles then colour inaccuracy occurs:

• Printing a wide-gamut image, such as AdobeRGB, as sRGB: Colours will be exaggerated and inaccurate.
• Printing an sRGB format image, as a wide-gamut profile, such as AdobeRGB: Colours will be muted.

Best practices

• Do not just remove EXIF and profile data from image files without understanding the consequences of this. If the colour spaces match then the colour characteristics will be maintained.
• Understand the capability of your printer and adjust software profile conversion to achieve the best print result.
• Businesses that manage their own photographers and do not accept outside src="Images, such as school photographers, can standardize profile setting. An example; setting AdobeRGB on all cameras and setting AdobeRGB as default in all workflow.
• Businesses that accept outside src="Images, such as standard photo labs, need to set a strategy to manage various input profiles.

IPS Order Manager has custom icc profile setting in the Pro version, to convert src="Images to custom printer profiles. If no profile is defined, IPS Order Manager maintains the image's embedded profile setting as it copies the image to the printer.