VideoPic Blog: The histogram and digital imaging process...

Last updated: 17th April 2026 (Application examples and technical updates)

The positive memories of filming with VHS inspired my priorities while preparing the next update to my filming series with Olympus cameras. My goal was to prepare the final look of my image and video footage in the camera, which meant more advanced color and exposure techniques. I decided to use two Olympus E-M5 II cameras for their unique film look. The color creator, tonal adjustments, and other settings make it easy to set the look and feel of my videos. I also came across a video from the YouTuber, Duade Paton, which encouraged me to prepare this short article in support of any future articles. It's a good idea to watch his video before you study this interesting subject.

PS: The next article in my filming series will be out soon...

Olympus E-M10 II with the M.Zuiko 17mm f1.8 lens. ISO200, f4.5, 1/400. What do we learn from the histogram?

Basic guidelines on the histogram and exposure

The histogram in the above image suggests an optimum exposure mix. The best way to confirm that is to analyze the histogram and the exposure mix. The goal is to evaluate the sensor's saturation level and SNR. The histogram plus the native ISO indicated a saturated sensor. This exposure mix produced excellent image quality with a wide depth of field at f4.5. The 4th exposure variable (late afternoon sun) was also ideal for the scene and the "painting with light" effect. This analysis would have been different at higher ISOs, even though the histograms might have looked the same.

Summarizing the exposure mix and histogram in the above image:

Histogram: A native ISO with no clipping and the histogram to the right.
Native ISO: The sensor was saturated (with a high SNR) at its native ISO.
Scene Luminance: The late afternoon sun and "painting with light" effect.
Aperture: The right focus point at f4.5 - The MFT depth of field advantage.
Image sharpness: A shutter speed of 1/400th worked well for sharp results.

It's impractical to evaluate image quality at higher ISOs with only the histogram. The alternative is to add sensor saturation and SNR to the mix with a personalized set of guidelines. The info in this article will help you identify and document "acceptable image quality" SNR values for your camera's sensor and ISO-to-SNR ratios. The reason is each camera and sensor has a unique noise floor.

Tip: LV (Light Values or scene luminance) - Discussed in the Duade Paton video.

Figure 1.

The above image signal flow diagram represents a high-level overview of the digital imaging process. It was created as a basic guide for photographers seeking an alternative to the oversimplified "bigger is better" or "capture more light" theory. The goal is to simplify managing technical aspects like image quality, dynamic range, and image noise. The image signal flow diagram highlights:

4 critical aspects of the digital imaging process (lens, sensor, processor, and Workspace).
the 3 variables exposing the image sensor (reflected light, aperture, and shutter speed).
the sensor and why the photons to electrons graph is critical for managing the sensor.
the exposure formula and the 4 variables we manage in the digital imaging process.
the role of the TruePic image processor and finalizing the digital imaging process.
the link between the image processor, the exposure controller, and Workspace.

The question photographers fail to ask is, what causes noise, and how do we manage it? The answer is to familiarize yourself with the graph below. While the "water bucket" example worked for the "size and capture" theory, it couldn't explain technical aspects like image noise, sensor saturation, and SNR. Duade Paton added the role of "Light Values" in managing the exposure mix, image noise (SNR), and ISO amplification. My suggestion is to add the following to his presentation:

A layer of sand at the bottom of the bucket to represent the sensor's noise floor.
Explain SNR and the effects of ISO amplification and lower light values on noise.
Sensor saturation and the link to SNR, "filling the bucket," or exposing the sensor.

PS: Saturating the sensor (filling the bucket) is linked to the exposure mix, not something magically like sensor size...

Figure 2.

Many photographers don't know that lower SNR values are the reason for visible noise. The sensor's noise floor is always present; we just don't see it at higher SNRs. In other words, the layer of sand in the bucket is more visible with less water. An alternative approach to having lower SNRs is to saturate the sensor (filling the bucket) at the camera's native ISO, wider apertures, and longer exposures. One could also accept more noise when upping the ISO and shutter speed (lowering the SNR).

Like color, it's good to master concepts like 18% gray exposures and tonal or gamma adjustments. The info in this article lets us explain and manage dynamic range in a similar way as noise. For example, the know-how in this article is a good start for informed discussions on dual ISO. Marketers tend to withhold information because product sales have priority over basic knowledge.

In the past, camera manufacturers used familiar filming phrases while introducing digital cameras to analog photographers. Unfortunately, the user manuals from Olympus and OM System continued using phrases like "ISO sensitivity" instead of more accurate digital phrases, like "ISO amplification." Study my articles and the photons-to-electrons graph (Figures 1 and 2) for more.

PS. Noise is NOT only linked to your ISO setting. (Consider the exposure mix, sensor saturation, and SNR)

Olympus E-M5 II with the amazing M.Zuiko 7-14mm f2.8 lens. ISO500, f3.2, 1/10 sec. I converted the enhanced Raw file in Workspace.

More about the digital exposure mix and the histogram

Always remind yourself that the ISO function evolved from a constant to a variable input. That's why I created the above illustration (Fig. 1) and replaced the analog with a digital exposure triangle. ISO amplification is the difference between a partially exposed sensor and an 18% gray saturated sensor. The camera uses 18% gray exposure values to accurately replicate ambient light and color.

Photographers were never "given" the chance to monitor the camera's sensor or manage variables like sensor saturation, noise, or dynamic range. The reason is the "bigger is better" narrative and social media distractions, like the histogram displays 8-bit JPEG data, ISO 100 on Olympus cameras differs from ISO 100 on others, or we shouldn't trust the histogram because it's inaccurate. These distractions are totally irrelevant when you start applying Live View and the histogram. Why?

A practical way to apply the exposure principles reviewed in this article is to think in terms of f-stops (1 EV steps) while preparing an exposure mix for challenging scenarios. For example, one can double the reflected light exposing the sensor by reducing the ISO by 1 stop. It's crucial to master the digital imaging process (Fig. 1) and the concept of managing the image sensor. Manual exposure mode is the most effective way to monitor specific variables with the histogram and Live View.

Tip: I get the best view of the images below when I study them on my 27' iMac...

Example 1 - Ambient light

I am always surprised at the level of ignorance or cognitive dissonance when people boast about using ISO 25600 on social media. For example, ISO 25600 means 7 stops of amplification, whereas the above images illustrate a 3 EV delta. The left image was amplified by 3 stops, or ISO 800, and the image to the right shows how much reflected light reached (exposed) the sensor at ISO 800.

The histogram shows the brightness of the pixels. That means all 4 exposure variables. The horizontal axis is the brightness levels from pure black on the left to pure white on the right (0-255 tonal range), and the vertical axis is the number of pixels at each brightness point on the horizontal axis.

How did I measure the reflected light exposing the sensor? Start by setting your exposure in auto or aperture mode. Change to manual exposure and apply these autoexposure values. The histogram will display the reflected light exposing the sensor as you turn the ISO back to its native value. I basically isolated the ISO to help the histogram measure the reflected light passing through the aperture and shutter onto the sensor. The flow diagram in Fig. 1 lets us identify and target specific phases in the imaging process, and manual mode helps us to display them in Live View and the histogram.

For example, the goal with ETTR is to saturate the sensor. That means more reflected light reaching the sensor. One option is fixing the ISO and adjusting the shutter, aperture, and scene luminance. Use the histogram to monitor the reflected light exposing the sensor. The next example is clipping. For example, it's possible to clip highlights with ISO amplification, which means the sensor is not clipping. Use the histogram to establish which of the 4 exposure variables are causing clipping.

PS. See the exposure formula for why I refer to 4 exposure "variables" and not only the 3 in the exposure-triangle.

Olympus E-30 with the Zuiko 50-200mm f2.8 lens. ISO100, f5.6, 4" (An ambient light example)

The above image shows it's possible to saturate the sensor in low light. It's incorrect to link noise to low light because longer exposure times saturate the sensor. It simply means the bucket doesn't need to be filled instantly because the sensor is designed to also saturate over longer periods. Higher ISOs, shutter speeds, and noise are, therefore, application-specific. It is critical to consider the reflected light reaching the sensor when setting your aperture and shutter speed mix. Random safety margins results in less light reaching the sensor, lower SNR values, or more visible noise.

Example 2 - Ambient light with +2EV illumination

The above example is exciting because I upped the scene luminance (4th exposure variable) with 2 EV. I used a similar method with the cuckoo clock image. For example, I used a powerful LED light in the above example and selective lighting (painting with light) with the cuckoo clock. Selectively using or applying the time of day is another example of "managing" your scene luminance.

It's worth noting the differences between the histogram in the above and the ambient light scene. The light value and SNR increases are shown in the histogram. The noise improvement in the above photo suggests a more sensitive sensor than one would think, considering social media inputs.

Photographers often need higher shutter speeds in normal daylight conditions. Modern cameras are more efficient at lower saturation and SNR values, which makes higher ISOs of up to +3 stops possible in these conditions. Study the inserted 200% cropped gray cards in the photos. If needed, the AI noise filter of Workspace works from ISO 800 upwards. We can also manage the image look by selectively adding noise to monotone (B&W) or monochrome photos. See the example further down.

I never consider social media talking points like noise, DR, diffraction, or image quality when I am out photographing with my Olympus cameras. I also don't have personalized ISO guides for my cameras. A basic understanding and the knowledge shared in this article are enough to benefit my results with any digital camera. For example, I only use Workspace and Affinity to process my images. Why would anyone prefer MFT unfriendly raw converters over Olympus colors and Workspace?

PS. I can make any camera's ISO test look worse than another while using equavilent camera settings... How?

Olympus E-30 with the Zuiko 50-200mm f2.8 lens. ISO100, f5.6, 1" (Another ambient light example)

Here is a list of things we can explain with this article:

- Knowing that the ISO can be a cause of clipping is huge.

- Test the sensor and select the SNR points you are happy to use.

- It is now possible to explain HDR photography with this knowledge.

- The goal with ETTR is to manage and improve sensor saturation and SNR.

- It is now possible to manage the amount of noise in your black & white shots.

- 18% gray exposures and calibrating the WB in WS insure consistent image colors.

- This article reviews a new exposure technique to control the DR in night photography.

- The unique histogram and the Live View functionality of Olympus cameras and Workspace.

Examples of applying the information in this article

It should be clear that the ISO does not generate noise. The ISO function amplifies the image signal. It is also used as a creative or control option. For example, it's possible to manage highlight clipping by upping the ISO while setting the exposure in manual mode and dialing the ISO back prior to taking the image. One would then finalize the exposure in Workspace. Another option is manual mode with auto ISO in cameras like the OM-3 and the E-M1 III. It allows us to maintain a constantly saturated sensor while offsetting the ISO with an exposure compensation and correcting it in Workspace. A constant SNR lets us use the ISO as a creative or control element in combination with Workspace.

The above technique came to mind as I studied the digital imaging process, the exposure formula, the ISO, and sensor saturation. I almost never use the above ISO technique because I am happy with the auto-gradation option or when managing the sensor and ISO separately. I did lower the ISO (0.7 EV) and corrected it in Workspace for the artist in the golden body paint photo...

Tip: Click on the photo collection below and click again for a large view of each.

Pen E-P7 - I used the know-how in this article to set my ISO range (ISO1250 - 3200). Workspace - The Color Creator & basic tonal tweaks.

It's important to keep in mind that modern sensors are so efficient that we don't need this knowledge for stunning results. The purpose of this article is a good understanding of the digital imaging process and the know-how to plan, solve, and optimize challenging and more complex applications.

My Pen E-P7 circus images are examples of complex scenes. They were all taken in fast-changing low-light conditions with changing colors and fast-moving subjects. I started by taking some test images to evaluate exposure combinations with a mix of exposure shifts, exposure compensation, and variable or fixed ISOs to define a basic exposure strategy for the activities and my Pen E-P7.

The RAW converters, Workspace and Affinity, share some functional similarities.

The color creator is perfect for LED lighting and illuminated colors. My circus and X-mas photos were photographed in an environment dominated by illuminated colors, which complicates WB readings and colors like red in the camera and post-processing. The color creator results are different for reflected and illuminated colors. It's a great option for both, but especially for illuminated colors.

I sharpened the above Affinity image with the high-pass filter. That said, my preferred RAW converter is Workspace. I changed to Affinity after cancelling my Adobe subscription in 2023. To my surprise, my editing and RAW conversions improved with Affinity. Interestingly, those pushing the "bigger is better" commercial theory also claim the Affinity RAW converter is not good enough.

Tip: See P66 (OM-3 manual) for the auto ISO with Exp. Comp and a constant SNR in M-mode.

Olympus Pen E-P7 with the M.Zuiko 45mm f1.8 lens. ISO2500, f1.8, 1/1000. I converted the RAW file in Workspace.

What makes Workspace special? The camera's TruePic imaging environment is part of Workspace and the enhanced RAW file. That means we can tweak our camera settings and finalize our exposure and tonal settings in Workspace and on a large PC screen. For example, we don't have the powerful tone curve function or the extended color options of the Workspace color adjust function in the camera. Workspace lets us do more in a replica of the camera's TruePic imaging environment.

It's exciting to study Olympus/OM System cameras and Workspace. For example, the histogram is only a tiny part of the creative and innovative features the Olympus Engineering team created over many years. For instance, it's unique for older MFT cameras to have access to the latest processing of the creative color strategy and advanced tonal and computational options from Olympus. Photographers also get access to the cameras' TruePic image processor via PC-RAW mode and Workspace.

PS. Fuji Raw Studio does not offer the same level of support for older cameras without the camera being connected to the PC.

The E-M5 & E-P7 Monotone/Monochrome with noise...

E-M5 with the M.Zuiko 12mm f2.0 lens. ISO12800, f9, 1/150. Monotone Picture Mode.

I took the above image with my Olympus E-M5. I selected the MKI because it has a larger noise floor than more recent cameras. The E-M5 histogram and Live View showed that the sensor received almost no reflected light at ISO 12800. It wouldn't surprise me if the sensor's actual exposure level were at the Absolute Sensitivity Threshold (Fig. 2). Will ISO 24600 increase the visible noise?

The next image was taken with the E-P7 in monochrome mode. My E-P7 review received more views than any of my other articles. The daily views tripled when the rumor surfaced that OM System might release an E-P8 in 2026. The monochrome function (Pen F, E-P7, and OM-3) is absolutely brilliant. It's also frustrating to see social media statements like "My favorite monochrome profile..." I'd rather see people experiment and manage their own monochrome look. Workspace and the enhanced raw format are perfect for tweaking and practicing your monochrome photography skills.

I couldn't confirm it, but read Olympus studied analog prints to create the realistically looking "noise patterns" of the Pen F, E-P7, and OM-3 monochrome function. I used the 2nd option below.

PS. Which of the older Olympus cameras have the best looking monotone noise?

E-P7 with the M.Zuiko 12mm f2.0 lens. ISO1000, f4.0, 1/20. Monochrome Picture Mode.

In summary, always plan and apply all 4 exposure variables controlling the camera's 18% gray exposure mix and practice using the histogram to follow the scene luminance exposing the sensor. The image signal flowchart and photons-to-electrons graph are basic tools to help us master key variables like sensor saturation, SNR, and the ISO (image signal amplification). While the ISO is part of the exposure formula, it does not directly control the reflected light to the sensor. Other key elements impacting the digital imaging process are the lens, sensor, TruePic processor, and Workspace.

OM System OM-3 with the tiny M.Zuiko 9-18mm f4 - 5.6 lens + PL filter. I converted the RAW file in Workspace - AUTO Gradation.

Folks, it should be clear why we only see some references speculating about the information in this article. The complete "bigger is better" commercial theory will fail as people learn more about digital photography. For example, I only use the "low" noise filter in Workspace and Olympus cameras. Noise and dynamic range have become nonissues to the experienced photographer, which explains why not all Olympus and OM System cameras have access to the Workspace AI noise filter.

Someone who recently changed to an OM System cameras made an interesting comment. The person said that one of the main aspects sparking his interest in MFT cameras was the knowledge and general creativity associated with Olympus and OM System photographers/communities.

Best

Siegfried

PS. I took these circus photos last weekend with a tiny kit consisting of the E-P7, the 17mm f2.8, and 45mm f1.8 lenses. Most MFT photographers don't appreciate the significance of the 2-stop depth of field advantage we have with Micro Four Thirds. For example, I took most of these images at f1.8 with the right focus points. That means I applied the 2-stop DOF and ISO/SNR (lower noise) MFT advantage with my E-P7. The Olympus cluster-autofocus function again proved to be a winner...