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Understanding Histograms in Photography

Understanding Histograms in Photography

Stephen Walton
December 28, 2023
Blog
5 mins

Digital photography has revolutionised how photographers capture and edit images, providing various benefits. The use of histograms is one of these advantages, as they offer a powerful tool in digital photography that provides a graphical representation of the tonal range in an image.

In this blog post, I want to share with you the significance of histograms and how they can be effectively utilised in Luminar Neo.

What is a Histogram?

A histogram in photography is a visual representation of the distribution of tones in an image. It shows the brightness of pixels in a photograph, ranging from black on the left to white on the right, with different shades of gray in between.

The horizontal axis represents the range of brightness values from 0 (black) to 255 (white), while the vertical axis shows the number of pixels at each brightness level.

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What do you use Histograms for in Photography?

Histograms are helpful tools for photographers as they provide valuable information about the exposure of an image. Here are some key points that explain what histograms are used for:

Exposure Evaluation

Histograms can help to determine the exposure of an image. The graph may be skewed to the left, indicating that the photo is underexposed (too dark), while a histogram skewed to the right suggests overexposure (too bright).

Contrast and Dynamic Range

The shape of the histogram can also provide insights into the contrast and dynamic range of the photo. A narrow histogram indicates low contrast, while a wide histogram with peaks and valleys suggests higher contrast.

Highlight and Shadow Detail

Examining the histogram can identify whether your image has lost detail in the highlights (right side) or shadows (left side). Clipped or “blown-out” highlights and shadows may result in losing essential information, and the histogram helps avoid such issues.

White & Colour Balance

The RGB histogram provides colour distribution in photos, useful for adjusting Saturation, White Balance or HSL Panel.

What are the Typical Histogram Shapes in Photography?

Understanding the shapes of histograms can provide valuable information about a photograph’s exposure and tonal distribution. Here are some typical shapes of histograms and their explanations:

Bell-shaped (Normal Distribution): The histogram in the picture looks like a bell curve. It shows that most tones are concentrated in the mid-tones, a good sign of a well-exposed image.
Left-skewed (Negative or Low-key Image): The image’s histogram is shifted towards the left, indicating more tones in the shadows. While this effect may be intentional to create a moody or low-key effect, it is essential not to lose details in the shadows.
Right-skewed (Positive or High-key Image): The histogram shows an increase in the number of tones in the bright areas of the image, causing it to shift towards the right. This often creates a light and airy atmosphere or suits high-key photography. However, it is essential to be careful and ensure that details in the bright areas are not lost.
Double-peaked (Bimodal Distribution): The histogram displays two distinct peaks, which suggests that two separate groups of tones are present in the image. This is common in high-contrast images, where dark and bright elements appear in the photo.
Sparse or Spiky (Low Contrast): It is possible to observe spikes or gaps on the histogram, which indicate that the image has a limited range of tones. This situation is common in low-contrast photos, where the tones are concentrated in specific areas, leading to a need for tonal variety. Adjustments to increase contrast can be beneficial to solve this.
Clipped Peaks (Overexposed or Underexposed): Peaks are cut off on the left (shadows) or right (highlights), which suggests that some details are lost in the clipped areas. Peaks on the right being cut off indicate overexposed areas, while peaks on the left being cut off indicate underexposed areas. It is vital to make adjustments to retain essential details.

How to use Histograms on your Camera

When it comes to image processing, a histogram is a valuable tool that can be used in post-processing and during the initial image capture. While reviewing images on a camera’s LCD screen is a common practice among photographers, it is only sometimes reliable since the brightness levels of different screens can vary.

In bright environments, it can be challenging to read the screen correctly. Histograms, however, provide a more accurate representation of an image’s exposure by displaying a graph of the distribution of tonal values.

They enable you to determine if your photo is overexposed, underexposed, lacking contrast, and more — thus making your post-processing workflow more efficient and effective.

It’s important to note that not all cameras display their histograms automatically. However, if your camera has a live view, you can usually access the real-time histogram by pressing the “Info” button (or equivalent) a few times.

To view the histogram for an image you just created, display the image and press the “Info” button (or equivalent) again. If you cannot locate the histogram, refer to your camera’s manual for further guidance.

Histograms in Luminar Neo

Histograms are an essential tool in Luminar Neo for adjusting exposure, brightness, contrast and color balance. They are handy when fine-tuning an image to ensure that all its details are preserved.

To access the histogram in the Edit module, navigate to the top of the main toolbar. If it’s not visible, right-click on the image and select “Show Histogram.” Click the histogram to choose between Luminance, RGB, and Red, Blue or Green views. Once at the Histogram, you can activate the live clipping mask by clicking on one of the two white circles in the top corner.

In addition to this, you can view a larger version of the luminance and separate color histograms in the Curves tab of the Develop and Develop RAW tool.

What are the Histogram types for?

Luminar Neo’s histograms come in various types, each providing specific information about the distribution of tones in an image. They serve as visual guides, offering insights into exposure, colour balance and tonal distribution, enabling photographers to create well-balanced and visually appealing photos.

Luminance Histogram

The most common type of histogram that displays an image’s brightness or luminance values. The x-axis ranges from black to white, showing the distribution of tones from shadows to highlights. Peaks and shifts in the luminance histogram provide insights into the exposure and tonal range of the image.

RGB Histogram

The RGB histogram displays the distribution of tones for each of the three primary colour channels: red, green and blue. It helps photographers analyse the image’s colour balance, saturation and overall colour distribution.

Separate Colour Channel Histograms

Luminar Neo offers not just an RGB histogram but also separate histograms for each colour channel, namely Red, Green and Blue. These histograms are helpful for photographers in making precise colour adjustments by detecting colour imbalances and ensuring that each channel contributes proportionately to the overall colour composition.

What is a Clipping Mask, and how do you use it in Luminar Neo?

In the Edit module, photographers can use a visual tool called a clipping mask to spot areas in an image where highlights or shadows are being clipped. This happens when an image is overexposed or underexposed, causing essential details to be lost. The clipping mask shows these areas as blue (for shadows) or red (for highlights), making it easier for users to identify and fix potential issues in their photographs.

Press the “J” key on your keyboard to activate the clipping mask. You can activate both the highlights and shadows clipping masks or trigger them separately by clicking on one of the white circles on the histogram.

Once activated, the live clipping mask will display the clipped areas as overlays in blue or red. The clipping mask will adjust in real time as you edit the image using any available tool in the Edit module.

Once you have created a clipping mask, you can easily adjust both highlight and shadow clippings using the Develop (Develop RAW) tool. For the highlight clipping, move the “Highlights” slider to the left for the highlight clipping to recover the details.

If this doesn’t work, try adjusting both the “Exposure” and “Whites” sliders. To fix the shadow clipping, use the same technique but with the “Shadows” and “Blacks” sliders. You can fine-tune the result by adjusting the Tone Curve in the Curve tab.

How to Edit Using Histograms in Luminar Neo

In Luminar Neo, there are several ways to utilise histograms during post-processing. Your chosen methods will depend on your photography style, personal workflow, and desired results. As a starting point, we recommend following the traditional workflow based on the earlier sections of this blog post.

1. Launch Luminar Neo and select the image you want to edit. Once you have done this, navigate to the “Edit” module and activate the histogram and clipping mask in the main toolbar. Review the information on the Luminance histogram and look for possible clipping on your image using the live clipping mask.

2. To adjust your image, open the Develop tool in the Essentials section of the main toolbar. Here, you can adjust the overall exposure of the image with the “Exposure” slider. The amount and direction of the adjustment will depend on the general shift of the histogram. You can also reduce as much clipping as possible with the “Highlights,” “Shadows,” “Blacks” and “Whites” sliders.

3. Depending on the shape of the histogram, use the “Contrast” slider to stretch or compress the tonal range in your image by pushing pixels towards the extremes of black and white or closer to the mid-tones.

4. If necessary, you can adjust the white balance of your image. To do this, switch your histogram to RGB type by clicking on the actual histogram. Review the distribution of the colour tones in your photo and use the “Temperature” and “Tint” sliders in the Colour tab to adjust it.

5. For more precise control over the luminance and colour adjustment, use the curves in the Curve tab.

Final Thoughts

Histograms have become an essential tool in digital photography, especially in platforms such as Luminar Neo.

These graphical representations of tonal distribution not only evaluate exposure, but also guide adjustments for contrast, dynamic range and colour balance. By understanding the various shapes of histograms, photographers can decode the nuances of their images.

Luminar Neo integrates histograms seamlessly into its user-friendly interface, providing several histogram types for precise insights. By embracing these tools, photographers can unlock their images’ full potential and reveal their beauty in every pixel.