Week 7: 09/11/2012

Lecture:  

Today's lecture was all about images and how light effects perception of an image or a scene (primary [seen first hand]) and colour.

Four main things that change in our sight depending on the light intensity and angle are: colours, shapes, details and textures.

There are very subtle differences between looking, seeing and observing:

Looking:  the process of arranging that which we can see

Seeing:  when we receive light energy and convert it into nerve impulses

Observing:  the process where we analyse, interpret, and classify the nerve impulses in terms of objects.  For example when we look into a mirror or see an effect such as a mirage.

When we are children, the observation stage is most prominent as we are still growing used to world around us.  However, throughout childhood it becomes less prominent as we then understand the world around us, and we no longer need to observe as thoroughly.  It would take a major change in our surroundings for us to make strong use of observation.  The only other time that observation would be really prominent is for someone who is studying something such as creative art, photography and the like.  They must observe to become aware.

Just as the brightness of sunlight changes throughout the course of the day, so does the colour and mood of an image that the sunlight is cast upon.  (See figure 1)

Figure 1 - How Sunlight Brightness Varies Throughout the Day and Changes the Appearance and Mood of an Image  

Typically the position of the sun throughout the day and alter the way we perceive and image.
Sentence from the lecture:  "As the sun rises and sets, light changes in very visible ways including a pronounced shift in colour."

Throughout the day, the position of the sun can also affect the position of the shadows it casts, i.e. during sun rise and sun set, the sun will cast long shadows.  During midday however, when the sun is at its highest point, the sun will cast short shadows.  (See figures 2, 3, 4 and 5)

Figure 2 - How Sunlight Height Affects What is Perceived at Pre-dawn  

Figure 3 - How Sunlight Height Affects What is Perceived at Morning  

Figure 4 - How Sunlight Height Affects What is Perceived at Mid-day  

Figure 5 - How Sunlight Height Affects What is Perceived at Twilight  

The changing nature of three basic factors create a play in/of light.  The most obvious and dramatic displays of changing qualities of light appear during sunrise and sunset.  These three factors mentioned are:  direction, contrast and colour.  (See figure 6)

Figure 6 - Light Play on the Grand Canyon  

Direction:  Quote from lecture: "The direction from which light strikes the subject is important."

The directions that a subject can be illuminated by light are: side-lighting, front-lighting and back-lighting.

Front-lighting: This occurs when the light source is behind the observer and shining directly onto the subject.  The light covers the subject evenly, thus revealing the detail.

Side-lighting: This creates strong shadows, which thus emphasize texture in an image, giving a greater sense of shape, dimension and depth.

Back-lighting:  This creates the most dramatic arrangements of light and shadow.  When using back-lighting, the source of light is behind the subject, creating silhouettes and other interesting effects.  (See figure 7, 8, 9, 10 and 11)

Figure 7 - Front-lighting  

Figure 8 - Front-lighting Vs Side-lighting  

Figure 9 - Side-lighting  

Figure 10 - Back-lighting  

Figure 11 - Back-lighting Continued  

Intense and directional, high-contrast light casts shadows with a hard edge.  If it is a bright, clear sunny day, the result shall be "hard" (high-contrasting) lighting.  Sharp details, rich, saturated colours and strong dramatic shadows are produced by the brightness of the light.

On an overcast day, there is softer low-contrast light.  Light is more evenly distributed and less bright because it is scattered by the clouds.  Differences between tones blend gradually in low-contrast light.  A more delicate mood is portrayed in these gentle shifts from light to dark areas.  (See figure's 12 & 13)

Figure 12 - Comparison Between High and Low Contrast  

Figure 13 - Example of Contrast Vs Detail  

Something the eye attempts to do is to adapt to the overall shifts in colour, automatically re-calibrating so that the perceived illumination approaches "white" i.e. white balance.

Although the eye is sensitive to the changes in colour of light, film is even more sensitive still.  A films response to colour is fixed at manufacture.

This thus explains why a slight orange tint is produced under tungsten light sources and a greenish tint under fluorescent light on daylight film.

Image processing can compensate for these shifts in colour.  (See figure 14)

Figure 14 - The Colour of Light  

The human eye is attracted to colours, especially those that are light an/or bright.

Mood can be powerfully impacted by colour, especially the mood communicated in the picture(s).  When creating a picture, remember that colour can affect mood.  However, colour can be culturally biased.  For example: black cats in Great Britain are classed as good luck and white cats are classed as bad luck.  But it is the opposite in America and Italy: Black is bad luck and white, good luck.

Yellow:  Can add a bright, cheerful tone to a visual message.
Red:  Often read as an exciting and warm colour.  However, depending on the context of the image it is used in, it can represent blood and death as well as other things.  Death is most normally portrayed by the colour black, however.
Green and Brown:  Restful colours often associated with nature.
Moody Blue:  Can lend a cool, subdued feeling.
Not So Moody Blue:  (See figure 15)
Colourise Effects:  (See figure 16)

Observation:  (See figure 17)
Selection:  (See figure 18)
Modification:  (See figure 19)

Figure 15 - Not So Moody Blue  

Figure 16 - Colourise Effects  

Figure 17 - Observation  

Figure 18 - Selection  

Figure 19 - Modification  

Conclusion:

• In an image, see more than the obvious subject.  
• Be aware of the dramatic impact of light, not just the light itself.  
• Be aware of the way light affects the way something is perceived at different points in the day.  
• Be aware that positioning of light can affect the way something is perceived.  
• Colours can affect the moods of each individual person.  

Week 6: 02/11/2012

Lecture:  

Today there was no lecture.  Instead, lecture time was dedicated to sitting the class test.

Lab:  

1. Opened up Adobe Soundbooth CS4  
1. Opened up the Sopran ascenddescend wav file  
2. Listened to the file and observed the shape of the wave  
3. Applied a compression effect to the full wave  
1. The compression effect was preset voice: moderate  
4. The sound now sounds slightly quieter (I think the amplitude may have changed) and the wave now looks compressed in height.  The wave still looks roughly the same length.  
1. Compression in regards to sound usually means an increase in density when the sound wave is travelling through a medium such as air  
5. Applied another compression effect to the full wave  
1. The compression effect was preset in your face: moderate  
2. The sound now sounds quieter again.  The height of the wave has again decreased.  
6. Applied another compression effect to the full wave  
1. The compression effect was preset acoustic attack: moderate  
2. The sound wave has been given the same effect again  
7. With the use of Google and research sites such as Wikipedia, I have researched the use of audio compressors and what they are meant to do and why.  
8. Compression is usually defined under two categories (from knowledge of SQA Higher Computing)  
1. Lossy Compression  
1. Where the data that is transmitted is reduced for transmission with loss of some data  
1. This is where the term lossy comes from (loss of data)  
1. Usually used for CD and MP3 encoding, Internet radio etc.  -  Wikipedia, 2011  
1. The data lost is not usually recognised by the user (sound perceiver).  This is why the system gets rid of the data.  It is technically useless and takes up needless space/memory in a storafe system  
2. Lossless Compression  
1. Where the data transmitted is not reduced and there is usually no loss of data  
1. This is where the term lossless comes from (no loss of data)  
3. These however, are compression types, but not compressors themselves  
9. You would more than likely want to use an audio compressor to reduce (compress) the dynamic range by reducing the loudest sounds  
10. The spectral display of the sound Sopran ascendescend is consistent with the waveform.  It shows me intensity by the colour or brightness on a frequency versus time axis (See figure 1)  
11. I opened up the english words wav  
12. The spectral display for this file (See figure 2) instantly stands out as completely different from the spectral display on the first file  
1. First of, as there are now pauses in the speech of the recording, there is spaces in-between each part of the spectral display's...fragments if you will.  
1. The colour intensity at the bottom of the spectral display completely differs from the top of the display.  The higher up the display you look, the less intense the colour/brightness  
1. I do not think speech is a musical sound.  Speech on its own is just a fundamental frequency, whereas musical tones/sounds are multiple harmonics of the fundamental frequency.  
13. On applying the convulsion reverb preset: clean-room-aggressive effect, the sound became slightly distorted in my opinion.  
14. On applying the convulsion reverb preset: roller disco aggressive effect, it sounded to me as if a man was speaking to me under a bridge tunnel made of metal.  It was like a reverb that would cause you to want to stop talking in my opinion.  
15. Reverb is created in a room by sound bouncing off of walls over and over again and then going to the perceiver of the sound, where the perceiver will hear the reverb  
16. Reverb is created by a computer on a wav file by creating a copy of the sound a slightly changing the frequency of the sound and then placing it on top of the original sound wave, creating the illusion of a reverb (possibly also through the use of distortion)  
17. Upon use of SpeechTranscript Transcribe, the system got most of the words said correct, but it did however add some words in the text that weren't actually spoken.  It basically tried to fit in gaps and think the words it created were what was actually said.  It basically used grammatical and basic English logic.  
1. This is not a simple computation.  Some system that can perform this task are not "trained" to understand words being said, but rather recognise an individual's voice.  This is normally used for security processes.  
1. Systems that recognise multiple voices and are "trained" to recognise words and change them to text usually are pre-programmed with several words and sentences etc.  
1. Microsoft® speech-to-text recognition on most systems was dependent on a single voice and the user to "train" it.  The user would be asked to read sentences and give commands to allow the system to understand how the user said certain words and phrases, as well as to give the system to recognise its users voice.  
2. The spectrogram for the original file is not that much different from the effect changed file shown in figure 2.  Most of the energy is shown at the bottom on the far right.  

Figure 1 - Spectral Display

Figure 2 - Spectral Display 2