The orange cube exercise

Summary

This video script introduces an exercise using an orange-painted cardboard cube to explore three types of color perception: object colors, illumination colors, and colors reaching our eyes. It challenges viewers to consider whether they perceive the cube's faces as differently colored due to light or as uniformly colored under varying illumination. The script delves into how our visual system interprets these colors, the concept of color constancy, and the impact of simultaneous contrast. It also touches on how artists might view scenes as arrays of light to translate into paint colors, suggesting the use of a cardboard mask to isolate light perception. The exercise serves as an introduction to a course on color, focusing on object and illumination colors, their attributes, and their significance in various fields.

Takeaways

• 🎨 The script introduces an exercise using an orange-painted cardboard cube to explore three types of color perception: object colors, illumination colors, and colors of light reaching our eyes.
• 🔍 The perceived color of an object changes based on the amount of light it receives, but we tend to perceive the object's color as uniform despite varying illumination.
• 👀 Our visual system interprets colors not just as light and dark but as objects of certain colors under specific illumination, such as 'white' light.
• 📐 The exercise challenges us to consider whether we see different colors on the cube's faces or the same color under varying light intensities.
• 🖼️ The script suggests that we perceive a uniform color through different intensities of light, akin to perceiving uniform, white, and black objects under varying illumination.
• 🌈 The colors we perceive as belonging to objects are referred to as 'object colors,' while those perceived as part of the illumination are called 'illumination colors'.
• 🗿 The script encourages observing other uniformly colored objects, like a statue, to understand if we perceive them as having different colors or as the same color under different light conditions.
• 🌟 Object color perception remains relatively constant across various viewing conditions, leading us to perceive it as an inherent property of the object.
• ⚖️ The constancy of object colors is not perfect, as demonstrated by the phenomenon of simultaneous contrast, where neighboring colors influence our perception.
• 🎨 Painters may choose to see a scene as a flat array of light patches of varying intensity and color, translating these into paint colors.
• 🖌️ The script recommends using a cardboard mask with a small hole to help see the light from different areas of the cube, divorced from the context of the cube as a whole.

Q & A

What is the main purpose of the exercise with the orange cardboard cube?

The main purpose of the exercise with the orange cardboard cube is to introduce the concept of three important kinds of colors: colors perceived as belonging to objects themselves, colors of the light falling on objects, and colors of the light reaching our eyes from objects.

How does the appearance of the cardboard cube's faces change, and what does this demonstrate?

The appearance of the cardboard cube's faces changes depending on the amount of light they receive. This demonstrates the difference between object colors, which are perceived as belonging to the objects themselves, and illumination colors, which are perceived as varying intensities of light.

What is the significance of perceiving the cube as having similarly colored faces illuminated by different amounts of light?

Perceiving the cube as having similarly colored faces illuminated by different amounts of light is significant because it shows our visual system's ability to perceive object colors consistently, even under varying illumination conditions.

What are the two patterns that we perceive superimposed on the same rectangle according to the script?

The two patterns perceived superimposed on the same rectangle are the pattern of uniformly colored objects (uniform orange, white, and black) and a pattern of light and shade, which is a pattern of illumination of varying intensity.

How does our visual system perceive an object of a certain color under illumination?

Our visual system perceives an object of a certain color under illumination by automatically presenting us with a perception of an object with a fixed, inherent property of color, illuminated by a certain color of light, typically 'white' light.

What is meant by 'object colors' and 'illumination colors' in standard scientific terminology?

In standard scientific terminology, 'object colors' refer to the colors perceived as belonging to objects themselves, and 'illumination colors' refer to the colors perceived as belonging to the light source illuminating the objects.

How does the perception of object color remain relatively constant through wide variations of viewing conditions?

The perception of object color remains relatively constant through wide variations of viewing conditions because our visual system perceives the object's intrinsic capacity to reflect various wavelengths of light, which is perceived as a seemingly fixed property of the object.

What is 'simultaneous contrast' and how does it affect the color perception of objects?

Simultaneous contrast is a phenomenon where the colors of neighboring areas impact the color we perceive an object as having. It demonstrates that our perception of object color is not entirely constant and can be influenced by the colors around it.

How can painters view a scene differently from the way we normally perceive objects and illumination?

Painters can view a scene as a flat array of patches of light of varying intensity and color, translating these colors of light reaching their eyes into colors of their paints, which is a different approach from the usual perception of objects and illumination.

What technique is suggested to help see the areas of the cube as light rather than as part of the whole cube?

The technique suggested to help see the areas of the cube as light is to look at them through a small hole in a piece of cardboard, which isolates the light from different areas of the cube from the context of the cube as a whole.

What is the ISCC/AIC Colour Literacy Project mentioned in the script, and what is its goal?

The ISCC/AIC Colour Literacy Project is an international initiative aimed at providing state-of-the-art educational resources that strengthen the bridges between the sciences, arts, design, and humanities, with a focus on color education.

Outlines

00:00

🎨 Understanding Object and Illumination Colours

This paragraph introduces an exercise using an orange-painted cardboard cube to explore three types of colours: object colours, illumination colours, and the colours perceived by the eye. It challenges the viewer to observe how the cube's appearance changes with varying light exposure and to consider whether the cube's faces appear differently coloured due to the light or if the cube itself appears to have uniformly coloured faces. The paragraph emphasizes that our visual system perceives objects as having a consistent colour under different lighting conditions, which is referred to as object colour. It also touches on the concept of illumination colour, which is the light's colour affecting the object's appearance. The exercise aims to deepen the understanding of how we visually interpret colours in relation to objects and light.

Keywords

💡Perceived Colour

Perceived colour refers to the colour that we see and interpret when we look at an object. It is not just about the light that falls on the object but also how our visual system processes this information. In the video, the perceived colour of the cardboard cube is mentioned as being darker on the face turned away from the light, which illustrates how the amount of light affects our perception of colour. The video uses this concept to explore how we visually process and interpret colour in different lighting conditions.

💡Object Colours

Object colours are the colours that we perceive as belonging to the objects themselves, independent of the light that falls on them. The video script describes how we perceive a uniformly coloured object, like the orange cube, as having a consistent colour regardless of the lighting. This concept is crucial because it helps us understand that our visual system interprets the inherent properties of objects, not just the light that illuminates them.

💡Illumination Colours

Illumination colours are the colours that we perceive as being part of the light source itself. In the context of the video, this concept is used to differentiate between the colour of the light source and the colour of the objects being illuminated. The video suggests that our visual system automatically interprets the colour of an object under a certain type of illumination, such as 'white' light, which is a common assumption in colour perception.

💡Visual Perception

Visual perception is the process by which our brain interprets the information received from our eyes. The video script discusses how visual perception allows us to see objects as having a consistent colour even when the lighting conditions change. It highlights the complexity of visual perception by showing that we do not just see a flat array of colours but perceive objects with depth and context.

💡Simultaneous Contrast

Simultaneous contrast is a phenomenon where the colours of neighbouring areas influence the colour we perceive an object as having. The video mentions this concept to explain how the constancy of object colours is not perfect and can be affected by the colours around it. This is an important aspect of colour perception as it shows how our visual system is influenced by the context in which colours appear.

💡Intrinsic Capacity

Intrinsic capacity, in the context of the video, refers to the inherent ability of an object to reflect various wavelengths of light. This concept is used to explain how we perceive the colour of an object as a result of its interaction with light. The video suggests that this capacity is what gives us a consistent perception of object colour across different viewing conditions.

💡Uniform Colour

Uniform colour describes an object that has a consistent colour across its surface. The video uses a cardboard cube painted with the same orange paint as an example of a uniformly coloured object. This concept is important because it helps to illustrate how our visual system can perceive different lighting conditions on the same object without altering the perceived colour of the object itself.

💡Pattern of Illumination

A pattern of illumination refers to the distribution of light and shade on an object's surface, which can create a visual pattern. The video script describes how we perceive these patterns as superimposed on the object, allowing us to see both the object's colour and the light's intensity. This concept is key to understanding how our visual system processes and interprets the interplay of light and colour.

💡Colour Constancy

Colour constancy is the ability of our visual system to perceive the colour of an object as relatively constant, even under varying lighting conditions. The video discusses how this constancy is not perfect, but it is a fundamental aspect of how we perceive the world. It allows us to recognize objects by their colour regardless of the lighting environment.

💡Context

Context, in the video, refers to the surrounding conditions or environment that can influence our perception of colour. The script mentions how the perceived colours of light are influenced by the new context, especially the brightness of the cardboard mask used in the exercise. This concept is important because it shows how our colour perception is not isolated but is influenced by the entire visual scene.

Highlights

Introduction to the perception of three important kinds of colors: object colors, illumination colors, and colors perceived by the light reaching our eyes.

Using a uniformly painted cardboard cube as an example to demonstrate how the appearance of color changes with varying light.

The perceived color of the cube is darker on the face turned away from the light, indicating the influence of illumination on color perception.

The importance of considering not just the flat array of colors but the perception of objects with inherent colors under specific illumination.

The visual system's automatic presentation of objects with certain colors under specific illumination, like 'white' light.

Definition of object colors and illumination colors in scientific terminology.

Observing uniformly-colored objects to understand the perception of object colors under varying illumination.

The perception of an object's intrinsic capacity to reflect light wavelengths as object color.

The relative constancy of object colors through wide variations of viewing conditions.

The impact of simultaneous contrast where neighboring areas' colors influence the perceived color of an object.

The ability to deliberately see a scene as a flat array of light patches of varying intensity and color.

Using a cardboard mask to help perceive areas of the cube as light, separating them from the context of the cube.

The influence of the new context, especially the brightness of the card, on the perceived colors of light.

Continuation of the course with a detailed look at the attributes of object and illumination colors, their interrelationships, and importance.

Introduction of the ISCC/AIC Colour Literacy Project and its mission to provide educational resources bridging sciences, arts, design, and humanities.

Transcripts

A good but neglected place to start a course on  colour is to ask what kinds of things we perceive  

as having colours. In this short video I’ll  describe a simple exercise I use to introduce  

three important kinds of colours, colours  perceived as belonging to objects themselves,  

to the light falling on objects, and to  the light reaching our eyes from objects.  

For this exercise I’ll refer to a cardboard cube  painted all over with the same orange paint,  

but you could adapt these instructions for  any uniformly coloured object. Examine the  

cube and observe how the appearance of each  face changes depending on the amount of light  

it receives and think carefully about  to how best to describe these changes.  

One common answer is that the “perceived colour”  of the cube is darker on the face turned away from  

the light, and certainly the light from this face  would match the light from a darker coloured chip  

under a given level of illumination. But it  would be missing something very important  

about visual perception to leave it at  that. Looking again at the actual cube,  

ask yourself: Do you perceive the cube itself to  have different-coloured faces, or do you perceive  

the cube to have similarly coloured faces  illuminated by different amounts of light?  

I’d argue that in this image we perceive  uniform orange, white and black coloured objects  

in the arrangement shown top right, and  also a pattern of light and shade, that is,  

a pattern of illumination of varying  intensity, as shown bottom right.  

Notice that we perceive these two patterns  superimposed in the same rectangle, [] as  

though we perceive the colours belonging  to the objects through the illumination.  

When we perceive an object visually, our  visual system doesn’t just present us with  

a flat array of lighter and darker colours  like a photograph, it automatically presents  

us with a perception of an object of a certain  colour under illumination of a certain colour,  

in this case “white” light. In standard scientific  terminology, these colours perceived as belonging  

to objects and to illumination are called object  colours and illumination colours respectively.  

You might like to look at other uniformly-coloured  objects and make similar observations. For  

example, do you perceive this statue  to be made of light and dark marble,  

or do you perceive it to be white marble  under varying intensities of illumination?  

The colour we perceive as belonging to  an object, through varying illumination,  

is the way in which we perceive the object’s  intrinsic capacity to reflect the various  

wavelengths of light. This object  colour perception remains relatively  

constant through wide variations of  viewing conditions, and as a result  

we tend to perceive it to be a seemingly  fixed, inherent property of the object.  

However, this constancy of object colours is not  perfect. In simultaneous contrast, for example,  

the colours of the neighbouring areas impact  the colour we perceive an object as having.  

Finally, while we would normally perceive  this scene as objects and illumination,  

we can also deliberately see it as a flat array  of patches of light of varying intensity and  

colour. As painters we might view it in this way  and translate these colours of light reaching our  

eyes into colours of our paints. If this is not immediately clear,  

look at the various areas of the cube through a  small hole in a piece of cardboard to help you  

to see these areas as light. The carboard  mask shows you the light reaching your eye  

from the different areas of the cube out  of the context of the cube as a whole.  

As always though, the colours of this light you  perceive will be influenced the new context,  

especially how bright the card appears. Having used the orange cube exercise to  

introduce these three important kinds  of colours at the start of my course,  

I continue the first session with a detailed look  at the various attributes of colours of objects  

and colours of lights, their interrelationships  and importance, again making use of the  

orange cube along with other illustrations. Stay tuned for many more colour exercises like  

this to be posted very soon on the website  of the ISCC/AIC Colour Literacy Project,  

an international initiative “to provide  state-of-the-art educational resources  

that strengthen the bridges between the  sciences, arts, design and humanities”.