The Willing Suspension of Disbelief

By: Mark Hunter
Excerpt from article written for Milori Inc.

It is relatively easy to look at a well reproduced, perfectly calibrated picture and know that it really looks great.  If you use a calibrated display to watch an Action DVD, you will find yourself getting caught up in the action of the movie and may unwittingly grip the arm of your chair during a chase scene, just to hang on.  If you are watching a suspense Thriller, you will find yourself unknowingly holding your breath and will feel your heart beat quicken and blood pressure rise as the stalker works his way toward the basement hideout.
 
In this nouveau-real environment, it's easy to get caught up in the action.  In fact, it is the whole "Escape" that makes the adventure worth taking.  Poet and author Samuel Taylor Coleridge called it "The Willing Suspension of Disbelief", meaning that we voluntarily allow ourselves to be brought into this manufactured world for a short while, just for the experience of it.
 
However, the "Willing Suspension of Disbelief" implies that the environment be believable as a prerequisite.  Image quality issues will cause us to lose our ability to accept what we are seeing as real.  An image that does not appear realistic, that does not appear like anything we could experience, will make it difficult for us to believe we are a part of the world we are watching.  Have you ever found yourself "falling out" of the suspension of disbelief due to distractions in a movie theatre?  Although those transient distractions are an inconvenience, image quality issues are a subconscious distraction that is ever-present, and they affect the suspension of disbelief during every experience.
 
Listed below are some common display device issues that affect the believability and realism of the image.  These issues cause us to lose the ability to "Suspend Disbelief" and can prevent us from getting caught up in the plot of a grand adventure.  Next to each of the visual images below is a description of what you are seeing in the picture.
 
Here are some of the most common image quality issues, how to detect them visually and through measurement, and what needs to be done to correct the image for maximum believability and realism.


Correct Reproduction1.png

This is the correct reproduction of Benjamin that accurately displays his real appearance. Notice the subtle gradations of skin tone on his checks and nose, the visible detail in his eyes and the naturalness of the fabric of his shirt. Also note the smoothness and uniformity of colour of the background behind Benjamin.

2.pngContrast Too High

Typical of displays set up to catch a buyer's attention, the Contrast of this display has been turned up to an excessive degree. Initially, this appears to create additional "punch" in the image, but extended viewing of the picture becomes quickly fatiguing, and possibly even damaging to the display device itself. Note the complete loss of detail in Benjamin's cheeks and nose as the highlight details are crushed.

Colour Too High3.png

The "Colour" setting of this display has been turned up too high, possibly in an effort to make the display appear "richer" and more saturated. One sign that the "Colour" control has been misadjusted is when male subjects appear to be wearing bright lipstick instead of having natural lip colour, or if normally fair skin appears sun burned.

4.pngColour Temperature Too High

Many displays are falsely set by Manufacturers to catch the eye in store showrooms, and not produce a natural and lifelike image. Among other things, this means that the Colour Temperature is typically adjusted way too high, which means that the image contains an excessive amount of Blue in the picture. 

Colour Temperature Too Low5.png

If a display has a "Colour Temperature" setting and it is adjusted to the "low" position, the image may not be correct for normal colour video. The picture to the left makes Benjamin appear in unnatural Sepia tones. Although it lends an air of apparent nostalgia to the image, it is not a correct reproduction.

6.pngSharpness Too High

A small amount of Sharpness boost (edge enhancement) may not negatively affect the image to an appreciable degree, but it must be understood that this is information that is not coming from the source material, and therefore may affect the "suspension of disbelief" that we would have if the image were more correct. However, here the Sharpness setting is clearly too high as can be see from the white shadow to the side of Benjamin's face.

Gamma Too High7.png

The luminance of the image across the grey scale is very important to proper image reproduction since the luminance represents such a large part of our image information. Here the gamma of the display is too high, which means that the mid-tones of the image are too dark. Note that the luminance of White and Black are still correct and that the colour is still where it should be. Only the luminance of the mid-tones is incorrect.

8.pngGamma Too Low

If the luminance through the mid-tones is too bright, the image will appear "washed out" and will not have the depth that draws a viewer in to the image. A low gamma setting can appear visually similar to having the Brightness control set too high.

Poor Grey Scale Tracking9.png

Non-linear grey scale tracking is a common problem, particularly with digital display devices. The issue is that different levels of grey are different colours. In this picture, the background behind Benjamin has a slightly Bluish tint to the darkest grey scale shades, turns Greenish through the mid-range, and ends up with a Reddish tint toward the top. Note how difficult these patterns would be to determine visually using just the picture of Benjamin (without the gradient background).

1.pngCorrect Reproduction

After all adjustments are made, we reach the state of an accurately reproduced image. Notice from the image how much more "present" and believable Benjamin appears. A properly calibrated image naturally assists in our "willing suspension of disbelief".