Month: April 2021

Today’s Question: Do you ever use the Lab color model?

Tim’s Quick Answer: I don’t typically convert images into the Lab color model, but that is actually the color model that is used in the background in terms of a color-managed workflow. That said, the Lab color model can be useful for a variety of tasks related to optimizing an image.

More Detail: I’m sure most photographers are familiar with the RGB color model, where colors are described based on how much red, green, and blue light is added together to produce a given color. Another common color model is CMYK, which describes the amount of cyan, magenta, yellow, and black ink must be combined to produce a given color in a print.

In the Lab color model there are three channels. The “L” channel specifies the luminance or brightness value for a given color. The “a” channel describes the color on a red/green axis, and the “b” channel describes the color on a blue/yellow axis.

The Lab color model is unique in that it is a device-independent color model. In other words, you can think of the color values as being absolute in terms of describing a specific color. By contrast, RGB values depend upon a specific profile, such as one that describes the unique behavior of a given monitor display. In other words, the actual color that results from combining specific values for red, green, and blue will vary based on the device and profile being used.

This is the reason the Lab color model is often at the center of a color-managed workflow. In effect, the color values in the image are interpreted to the Lab color model, and then converted again to color values to send to the printer based on a profile for the specific printer, ink, and paper combination being used.

You can also convert an image to the Lab color model with software such as Photoshop. One of the advantages of doing so is that the tonal information is separated from the color information. So, for example, you could focus your sharpening on the L (luminance) channel to ensure that sharpening doesn’t alter the colors in an image.
Some photographers also prefer to use Lab for color correction, since the two color channels are separate from the luminance channel. And you can apply various creative effects using special techniques with the Lab color model.

For my purposes the Lab color model doesn’t provide a benefit that would cause me to convert an image to Lab. However, as noted above, I absolutely benefit from the Lab color model in my photography, since Lab is the foundation of a color-managed workflow.

Today’s Question: Can you create more than five different color labels?

Tim’s Quick Answer: Yes, you can create more than the five “standard” color labels, though doing so may cause some confusion in terms of how the color labels are displayed in the software you’re using to manage your photos.

More Detail: Most software designed for managing photos includes support for a color label feature, enabling you to mark photos with a red, yellow, green, blue, or purple color label.

However, those color labels aren’t actually colors at all. Rather, the color label represents the Label field in metadata, which like other metadata fields simply stores a series of characters. As a result, it is possible to use the color label feature in a way that goes beyond the way this feature is typically implemented.

What that really means is that you could put any word you’d like into the Label field in metadata. However, doing so won’t likely provide the expanded functionality you might have been hoping for.

As an example, Lightroom Classic uses the name of the color as the word that is added to the Label field when you apply a color label. So, if you assign a red color label to a photo, the word “Red” is added to the Label field.

You could also manually add any word you’d like to the Label field. For example, you might want to use the Label field to identify photos that need to be retouched by putting the word “Retouch” into the Label field.

Depending on the software you’re using, there may actually be some value to using this type of approach. For example, while adding the word “Retouch” won’t add a color label that displays one of the standard colors, the image will still be marked. Any photo in Lightroom Classic that has a value in the Label field in metadata that does not match the definitions used for the color label feature will be marked with a white color label.

That non-standard color label can even be filtered in Lightroom Classic in a couple of ways. Using the Attribute filter tab for the Library Filter bar, for example, you can choose to show images with the Custom (white) color label. In addition, on the Metadata tab you can select Label from the header for one of the columns, and then see a list of all color label names that have been used for the photos that are currently displayed.

You could even switch between different sets of color label definitions at different times, based on the task you’re currently performing in your workflow.

For example, let’s assume you want to use color labels with different labels based on tasks related to both organizing your photos and optimizing your photos. You could create a color label set for each in Lightroom Classic using the Edit Color Label Set dialog (Metadata > Color Label Set > Edit). You can create and then select the “Organizing” versus “Optimizing” color label set depending on the task you’re performing, and apply or review or filter based on those color labels.

With this approach, when you are working with the “Organizing” color label set, photos with color labels based on the “Optimizing” set will show a white color label, and the reverse would be true when working with the “Optimizing” color label set.

So, it is indeed possible to create and use more than five color labels, with some limitations. Just keep in mind if you’re thinking of adopting this type of approach that you can still only assign a single color label to a given image.