CUVPHI07B Process photo images to work print/file stage
Taught by Ralf Hesse
This unit describes the skills and knowledge required to use techniques for image processing and focuses on technical aspects including chemical and electronic processes, sensitometry and optoelectronics. It is a specialisation unit and refers to specific equipment and techniques used for making photo work-print images.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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D
aylight_AsShot - Temperature 5250 Tint +8
D
aylight_Daylight - Temperature 5500 Tint + 10
D
aylight_Auto - Temperature 4950 Tint 0
D
aylightAuto_AsShot - Temperature 5200 Tint + 10
D
aylight_Corrected Temperature 5300 Tint -10
1. 2. 3. 4. 5.
Daylight as shot - looks fairly close to colour Daylight Auto - Is a bit too blue on the back wall Daylight Daylight - Looks a bit blown out Daylight Corrected - Back wall looks true to colour Daylight Auto As Shot - Looks a bit blown out -
Temperature 5250 Tint + 8 Temperature 4950 Tint 0 Temperature 5500 Tint + 10 Temperature 5300 Tint -10 Temperature 5200 Tint + 10
My preference is for Daylight Corrected. The Auto Shot looks to harsh compared to the Corrected image. The grays seem to be faithfully rendered in the Corrected shot. There didn’t appear to be any noise in the photos.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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S
hade_AsShot - Temperature 7150Tint + 10
S
hadeAuto_AsShot Temperature 5600 Tint +15
S
hade_Auto- Temperature 5750 Tint + 0
S
hade_shade - Temperature 7500 Tint +10
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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S
hade_Corrected Tint -1
Temperature
5700
1. Shade_AsShot - Temperature 7150Tint + 10 2. Shade_Auto- Temperature 5750 Tint + 0 3. Shade_shade - Temperature 7500 Tint +10 4. Shade_Corrected Temperature 5700 Tint -1 5. ShadeAuto_AsShot Temperature 5600 Tint +15 My preference is for Shade As Shot it looks to warm compared to the Corrected image. The greys seem to be faithfully rendered in the Shade as Shade shot. There doesn’t appear to be any noise in the shots. Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Too cool Cloudy_ Auto too yellow
C 6
C T
loudy_AsShot - Temperature
loudy_Auto -
050 Tint +8
emperature 5500 Tint 3 Too cool CloudyAuto_ AsShot
too yellow
C T
C T
loudyAuto_AsShot
loudy_Cloudy-
emperature 5150 Tint +8
emperature 6500 Tint +10
Most natural
C T
loudy_Corrected emperature 5800 Tint +10
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Cloudy_AsShot-4488.jpg
Cloudy_Auto-4488.jpg
Cloudy_Cloudy-4488.jpg
Cloudy_Corrected-4489.jpg
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Cloudy_Corrected-4489.jpg
CloudyAuto_AsShot-4489.jpg
In the instance of the cloudy photographs the Cloudy Corrected is the most faithful to colour. There is noise in the photograph. The Cloudy as shot was too yellow as was the Cloudy_Cloudy The Cloudy Auto and CloudyAuto_AsShot were too cool The best rendition was the Cloudy_Corrected.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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T
ungsten_AsShot - Temperature 3150 Tint + 4
T
ungsten- tungsten Temperature 7500 Tint +10
T
ungsten_Auto - Temperature 2850 Tint + 0
T
ungstenAuto_As Shot tungsten Temperature 4100 Tint + 4
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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T
ungsten_Corrected Temperature 3100 Tint -4
1. 2. 3. 4. 5.
Tungsten_AsShot - Temperature 3150 Tint + 4 Tungsten_Auto - Temperature 2850 Tint + 0 Tungsten- tungsten Temperature 7500 Tint +10 Tungsten_Corrected Temperature 3100 Tint -4 TungstenAuto_As Shot Temperature 4100 Tint + 4
My preference is for Tungsten Corrected it looks to more natural than the others. The yellow boards seem to be faithfully rendered in the Corrected shot. There does appear to be noise in the particularly the Auto one
The Tungsten_Auto is too grey on the back wall and not true to colour as is the Tungsten_Tungsten too grey on the back wall plus the wood is not rendered correctly. The TungstenAuto_AsShot, is too yellow. My preference is for Tungsten Corrected it looks to more natural than the others.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Fluro_AsShot - Temperature 3150 Tint + 4
F
luro-fluro Temperature 3800 Tint +21
F
luro_Auto - Temperature 3550 Tint + 16
F
luroAuto_As Shot Temperature 3900 Tint + 24
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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F
luro_Corrected Tint +11
Temperature
3600
1. Fluro_AsShot - Temperature 3150 Tint + 4 2. Fluro_Auto - Temperature 3550 Tint + 16 3. Fluro-fluro Temperature 3800 Tint +21 4. Fluro_Corrected Temperature 3600 Tint +11 5. FluroAuto_As Shot Temperature 3900 Tint + 24 My preference is for the fluro_fluro in this example. It seems to be more natural in colour and has a lot of clarity. the Fluro_AsShot, seemed to be too blue and clinical. The fluro_Auto was better and a bit warmer. The Fluro_corrected seemed to be a bit green and the FluroAuto_AsShot didn’t seem too bad.
The higher numbered Temperatures in this instance seemed be better examples and more pleasing to the eye. There was noise in both photographs, I don’t know whether because of low light in the hallway, or lack of focus, or the ISO being too low?
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Mixed_AsShot - Temperature 3950 Tint + 33
Mixed_Mixed(fluro setting) - Temperature 3800 Tint + 21
Mixed_Auto - Temperature 3250 Tint + 0
M
ixedAuto_AsShot 4000 Tint + 11
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Temperature
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M
ixed_Corrected Temperature 4050 Tint - 4 - becomes too green
The two photos on the following page contact sheet show that the photos which are too green are as follows. MixxedAuto_AsShot - Temperature 4000 Tint + 11becomes too green Mixed_Corrected Temperature 4050 Tint - 4 - becomes too green Mixed_AsShot - Temperature 3950 Tint + 33 seems to be more natural Mixed_Auto - Temperature 3250 Tint + 0 too green Mixed_Mixed(fluro setting) - Temperature 3800 Tint + 21 bit blown out There is noise in all of the photos. I am not sure if it is because the iso should be higher than 125.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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The two below are too green with tints of MixxedAuto_AsShot - Temperature 4000 Tint + 11becomes too green Mixed_Corrected Temperature 4050 Tint - 4 - becomes too green Mixed_AsShot - Temperature 3950 Tint + 33 seems to be more natural Mixed_Auto - Temperature 3250 Tint + 0 Mixed_Mixed(fluro setting) - Temperature 3800 Tint + 21 There is noise in all of the photos. I am not sure if it is because the iso should be higher than 125.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Flash_AsShot - Temperature 6250 Tint + 12 a bit dark as the flash didn’t fire despite being in a very dark area underground
Flash_Auto - Temperature 3800 Tint + 0 is too blue in the cast and too cool in colour
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Flash_Flash- Temperature 5500 Tint + 0 becomes more natural and faithful to colour despite the noise and camera shake
F
lash Auto_AsShot - Temperature 4550 Tint + 3. This one is fairly natural and I think my preference overall.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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F
lash_Corrected- Temperature 4300 Tint _4. This one is too cool in colour.
On the following page my proof sheet shows by comparion the following results Flash_AsShot - Temperature 6250 Tint + 12 a bit dark as the flash didn’t fire despite being in a very dark area underground and there is noise in all photos. Flash_Auto - Temperature 3800 Tint + 0 is too blue in the cast and too cool in colour Flash_Flash- Temperature 5500 Tint + 0 becomes more natural and faithful to colour despite the noise and camera shake Flash Auto_AsShot - Temperature 4550 Tint + 3. This one is fairly natural and I think my preference overall. Flash_Corrected- Temperature 4300 Tint _4. This one is too cool in colour.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Flash_AsShot - Temperature 6250 Tint + 12 a bit dark as the flash didn’t fire despite being in a very dark area underground and there is noise in all photos. Flash_Auto - Temperature 3800 Tint + 0 is too blue in the cast and too cool in colour Flash_Flash- Temperature 5500 Tint + 0 becomes more natural and faithful to colour despite the noise and camera shake Flash Auto_AsShot - Temperature 4550 Tint + 3. This one is fairly natural and I think my preference overall. Flash_Corrected- Temperature 4300 Tint _4. This one is too cool in colour.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Written Report In the 7 cases below, 3 cases my preferences were for the Corrected Version of the photograph (noted in italics) and 3 preferences were for the As Shot setting on the camera, in as much as it had been dialled into the camera for the lighting conditions of the day. 1 photo had a preference for Fluro_Fluro I think generally the corrected versions were truer in rendition and more faithful to colour than the other photographs. Daylight: My preference is for Daylight Corrected. The greys seem to be faithfully rendered in the Corrected shot. The Auto Shot looks to harsh compared to the Corrected image. Shade My preference is for Shade As Shot it looks to warm compared to the Corrected image. The greys seem to be faithfully rendered in the Shade as Shade shot. Cloudy In the instance of the cloudy photographs the Cloudy Corrected is the most faithful to colour. The Cloudy as shot was too yellow as was the Cloudy_Cloudy The Cloudy Auto and CloudyAuto_AsShot were too cool The best rendition was the Cloudy_Corrected. Tungsten My preference is for Tungsten Corrected it looks to more natural than the others. The yellow boards seem to be faithfully rendered in the Corrected shot. There does appear to be noise in the particularly the Auto one. The higher numbered Temperatures in this instance seemed be better examples and more pleasing to the eye. There was noise in both photographs, I don’t know whether because of low light in the hallway, or lack of focus, or the ISO being too low Fluroescent My preference is for the fluro_fluro in this example. It seems to be more natural in colour and has a lot of clarity. the Fluro_AsShot, seemed to be too blue and clinical. The fluro_Auto was better and a bit warmer. The Fluro_corrected seemed to be a bit green and the FluroAuto_AsShot didn’t seem too bad. Flash Flash_AsShot - a bit dark as the flash didn’t fire despite being in a very dark area underground and there is noise in all photos.Flash_Auto - too blue in the cast and too cool in colour Flash_Flash- becomes more natural and faithful to colour despite the noise and camera shake Flash Auto_AsShot - This one is fairly natural and I think my preference overall. Flash_Corrected- Temperature 4300 Tint _4. This one is too cool in colour. Mixed MixedAuto_AsShot - becames too green, Mixed_Corrected becomes too green, Mixed_AsShot - seems to be more natural, Mixed_Auto - too green..Mixed_Mixed(fluro setting) - bit blown out There is noise in all of the photos. I am not sure if it is because the iso should be higher than 125.
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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“Quote from cambridgeincolour.com” White balance (WB) is the process of removing unrealistic color casts, so that objects which appear white in person are rendered white in your photo. Proper camera white balance has to take into account the "color temperature" of a light source, which refers to the relative warmth or coolness of white light. Our eyes are very good at judging what is white under different light sources, but digital cameras often have great difficulty with auto white balance (AWB) — and can create unsightly blue, orange, or even green color casts. Understanding digital white balance can help you avoid these color casts, thereby improving your photos under a wider range of lighting conditions. Relative intensity has been normalized for each temperature (in Kelvins). Note how 5000 K produces roughly neutral light, whereas 3000 K and 9000 K produce light spectrums which shift to contain more orange and blue wavelengths, respectively. As the color temperature rises, the color distribution becomes cooler. This may not seem intuitive, but results from the fact that shorter wavelengths contain light of higher energy.
Why is color temperature a useful description of light for photographers, if they never deal with true blackbodies? Fortunately, light sources such as daylight and tungsten bulbs closely mimic the distribution of light created by blackbodies, although others such as fluorescent and most commercial lighting depart from blackbodies significantly. Since photographers never use the term color temperature to refer to a true blackbody light source, the term is implied to be a “correlated color temperature” with a similarly colored blackbody. The following table is a rule-of-thumb guide to the correlated color temperature of some common light sources: Color Temperature Light Source 1000-2000 K Candlelight 2500-3500 K Tungsten Bulb (household variety) 3000-4000 K Sunrise/Sunset (clear sky) 4000-5000 K Fluorescent Lamps 5000-5500 K Electronic Flash 5000-6500 K Daylight with Clear Sky (sun overhead) 6500-8000 K Moderately Overcast Sky 9000-10000 K Shade or Heavily Overcast Sky IN PRACTICE: JPEG & TIFF FILES Since some light sources do not resemble blackbody radiators, white balance uses a second variable in addition to color temperature: the green-magenta shift. Adjusting the green-magenta shift is often unnecessary under ordinary daylight, however fluorescent and other artificial lighting may require significant green-magenta adjustments to the WB. Auto White Balance Custom Kelvin Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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Tungsten Fluorescent Daylight Flash Cloudy Shade Fortunately,most digital cameras contain a variety of preset white balances, so you do not have to deal with color temperature and green-magenta shift during the critical shot. Commonly used symbols for each of these are listed above. The first three white balances allow for a range of color temperatures. Auto white balance is available in all digital cameras and uses a best guess algorithm within a limited range — usually between 3000/4000 K and 7000 K. Custom white balance allows you to take a picture of a known gray reference under the same lighting, and then set that as the white balance for future photos. With “Kelvin” you can set the color temperature over a broad range. The remaining six white balances are listed in order of increasing color temperature, however many compact cameras do not include a shade white balance. Some cameras also include a “Fluorescent H” setting, which is designed to work in newer daylight-calibrated fluorescents. The description for the above white balances are just rough estimates for the actual lighting they work best under. In fact, cloudy could be used in place of daylight depending on the time of day, elevation, or degree of haziness. In general, if your image appears too cool on your LCD screen preview (regardless of the setting), you can quickly increase the color temperature by selecting a symbol further down on the list above. If the image is still too cool (or warm if going the other direction), you can resort to manually entering a temperature in the Kelvin setting. If all else fails and the image still does not have the correct WB after inspecting it on a computer afterwards, you can adjust the color balance to remove additional color casts. Alternatively, one could click on a colorless reference (see section on neutral references) with the “set gray point” dropper while using the “levels” tool in Photoshop. Either of these methods should be avoided since they can severely reduce the bit depth of your image. IN PRACTICE: THE RAW FILE FORMAT By far the best white balance solution is to photograph using the RAW file format (if your camera supports them), as these allow you to set the WB *after* the photo has been taken. RAW files also allow one to set the WB based on a broader range of color temperature and green-magenta shifts. Performing a white balance with a raw file is quick and easy. You can either adjust the temperature and green-magenta sliders until color casts are removed, or you can simply click on a neutral reference within the image (see next section). Even if only one of your photos contains a neutral reference, you can click on it and then use the resulting WB settings for the remainder of your photos (assuming the same lighting). CUSTOM WHITE BALANCE: CHOOSING A NEUTRAL REFERENCE A neutral reference is often used for color-critical projects, or for situations where one anticipates auto white balance will encounter problems. Neutral references can either be parts of your scene (if you’re lucky), or can be a portable item which you carry with you. On the other hand, pre-made portable references are almost always more accurate since one can easily be tricked into thinking an object is neutral when it is not. Portable references can be expensive and specifically designed for photography, or may include less expensive household items. Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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An ideal gray reference is one which reflects all colors in the spectrum equally, and can consistently do so under a broad range of color temperatures. Common household neutral references are the underside of a lid to a coffee or pringles container. These are both inexpensive and reasonably accurate, although custom-made photographic references are the best (such as the cards shown above). Custom-made devices can be used to measure either the incident or reflected color temperature of the illuminant. Most neutral references measure reflected light, whereas a device such as a white balance meter or an "ExpoDisc" can measure incident light (and can theoretically be more accurate). Care should be taken when using a neutral reference with high image noise, since clicking on a seemingly gray region may actually select a colorful pixel caused by color noise: Low Noise (Smooth Colorless Gray) High Noise (Patches of Color) If your software supports it, the best solution for white balancing with noisy images is to use the average of pixels with a noisy gray region as your reference. This can be either a 3x3 or 5x5 pixel average if using Adobe Photoshop. Certain subjects create problems for a digital camera's auto white balance — even under normal daylight conditions. One example is if the image already has an overabundance of warmth or coolness due to unique subject matter. The image below illustrates a situation where the subject is predominantly red, and so the camera mistakes this for a color cast induced by a warm light source. The camera then tries to compensate for this so that the average color of the image is closer to neutral, but in doing so it unknowingly creates a bluish color cast on the stones. Some digital cameras are more susceptible to this than others. Automatic White Balance Custom White Balance (Custom white balance uses an 18% gray card as a neutral reference.) A digital camera's auto white balance is often more effective when the photo contains at least one white or bright colorless element. Of course, do not try to change your composition to include a colorless object, but just be aware that its absence may cause problems with the auto white balance. IN MIXED LIGHTING Multiple illuminants with different color temperatures can further complicate performing a white balance. Some lighting situations may not even have a truly "correct" white balance, and will depend upon where color accuracy is most important. Under mixed lighting, auto white balance usually calculates an average color temperature for the entire scene, and then uses this as the white balance. This approach is usually acceptable, however auto white balance tends to exaggerate the difference in color temperature for each light source, as compared with what we perceive with our eyes. Exaggerated differences in color temperature are often most apparent with mixed indoor and natural lighting. Critical images may even require a different white balance for each lighting region. On the other hand, some may prefer to leave the color temperatures as is.
Source is http://www.cambridgeincolour.com/tutorials/white-balance.htm
Sue McArthur - CUVPHI07B - Process Photoimages to work print/file stage
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