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E-Photography - Frequently asked Questions

Color Cast
A colour cast is created when the whole image is lit by coloured lighting. Colour casts are can be useful for adding mood to a picture.  But sometimes the colour cast has the wrong effect and needs to be removed.

The colour of sun light varies during the day.

  • At midday, direct sunshine through a clear sky gives a white light.
  • The more cloud cover, the more scattered light there is.  The scattering absorbs the red light and introduces a blue cast.
  • Natural light has a red cast at sunrise and sunset as the light has to travel a longer distance through the atmosphere – the dust and water vapor absorbs the blue light.  Sunsets are more pronounced because more dust accumulates in the air during the day.

Artificial light has a pronounced colour cast.

  • Candles and oil lamps give off a very orange light.
  • Tungsten lights are very yellow.
  • Photofloods and electronic flash are also slightly more yellow than white light but not noticeably so to the human eye.
  • Fluorescent lighting is quite complicated as it misses several frequencies, and also varies over time (at 60 cycles per second).  It generally creates a green cast on film.
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Colour also depends on reflected light.  When standing in outdoor shade a subject is likely to be lit by light reflected off grass and trees.  This gives a green cast (in addition to the blue cast from scattered light).  If there are painted walls nearby, the image will also be influenced by the colour of the walls.

The human eye adapts to colour casts so we do not normally notice them.  In contrast film does not adapt, so film images can have more pronounced colors than the photographer noticed at the time.  One of the skills photographers develop is an increased sensitivity to the colour of the light.

Different films respond to differently to the colour of light. Daylight balanced film is set up so that the colours of pictures taken at midday with a clear sky and direct sunlight (i.e. white light) appear natural.  Tungsten balanced film counteracts the yellow effect of tungsten lights so that pictures taken in that environment appear natural.  There are also subtle differences between the various daylight balanced films, and photographers learn which films work best for them in particular circumstances.

Filters can be used to change the colour cast of an image, either to remove an unwanted cast or to add mood.  The most popular are the 81 series (A-E) which add increasing degrees of warmth (yellow) to the image.  A sunset filter (197) can also add spice to many bland images.

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Colour Space
In a digital image the colour of each pixel is stored as a sequence of numbers.

For example, in the sRGB colour space there are three numbers (R,G,B).  Each number can have a value from 0 to 255.  The R gives the amount of red, the G gives the amount of green and B gives the amount of blue.  The sRGB colour space represents the range of colours that can be shown on a monitor, a digital projector, or printed on low end printers.

The Adobe RGB colour space also uses three numbers to represent the red, green and blue elements. ' But the interpretation of the values is different.  For example, a red value of 100 in the Adobe color space refers to a different colour than in the sRGB colour space.

Consequently for colours to be shown correctly the colour space needs to be saved with the image, and the program displaying the image needs to interpret the values correctly (IrfanView and Photoshop both make use of the colour space settings).  An image that is displayed with the wrong colour space settings will look too saturated or too washed out.

High end printers can reproduce additional colours that cannot be viewed on a monitor.  We say that the printer has a wider colour gamut.  Printers normally produce their colours by overlaying cyan, magenta, yellow and black inks.  For this reason high end print work is specified in a CMYK (Cyan, Magenta, Yellow, Black) colour space.  In reality it is not a single colour space, as the colours associated with the values depends on the printer and inks used.

The Adobe RGB colour space was designed to have a wide enough gamut to encompass both sRGB and CMYK. Images intended for print can be edited in the Adobe color space and then converted to CMYK for final output (i.e. step 6 of the workflow).

Clearly it can be difficult to edit an image on a monitor if you are unable to see the full range of colours in the image!  For this reason Photoshop will adjust the colours so that the full gamut can be displayed on the monitor.  But the colours are then not true to life!  Unless you really need to reproduce colours outside of the sRGB range it is advisable to use sRGB as your working colour space.

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Filters and Digital Cameras
Most filters can be simulated in Photoshop.  The polarizing filter is the only exception as the information on the polarity of light is lost at the time of recording the image.  So always shoot with a polarizer if the situation warrants it.

For the other filters, you get better quality by applying the filter digitally (it’s always dust free).  It also means that you can experiment to get exactly the effect that you want.  It is also cheaper.

The Photo Filter adjustment layer is an easy way to simulate the common filters, but with a little more work every filter effect can be achieved (e.g. motion blur together with a layer mask will give a speed filter effect).

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Image Sharpness
How to tell if your image is a good digital image via the monitor (I find the image looks good on the monitor, but when I do a print it isn’t sharp enough)

The camera monitor is too small to see whether an image is sharp.  Cameras have a zoom function so you can zoom in to see the individual pixels but then you only see part of the image.  It is very time consuming to properly check an image on the camera for sharpness.

It is far better to load the images onto a computer and examine them at 100% (Ctrl+Alt+0) on a good monitor before deleting the duffs.  Don't use a TV for this purpose.

Before printing, resize the image (Image Size) to the required physical dimensions with a resolution of at least 200 pixels/inch (preferably 300 pixels/inch).  Then sharpen the image (Filter/Sharpen/Unsharp mask) and examine it at 100% to see if there are any problems.  To get a good impression of the whole image view it at 50%, 25% or 12.5%.  Don't use non-even fractions like 33% as it can distort the apparent sharpness of the image.

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Monitor Resolution
What resolution should I set my monitor to?

LCD (liquid crystal display) monitors have a grid of pixels that determine the native resolution.  You should use the native resolution. If you set the monitor to any other resolution, images will not display very accurately.  CRT (cathode ray tube) monitors are more adaptable and can be set to various resolutions.  When working in Photoshop it is useful to use a resolution higher than 1024x768 so that you can display the image at 100% and still have space to include Photoshop windows such as Tools and Layers.  Choose a resolution like 1600x1200 which has the same 4x3 proportions as 1024x768.  If you choose a resolution like 1280x1024 which has a 5x4 proportion the image will be stretched and alter your perception of the image.

To change the resolution in Windows, right click on the desktop and select Properties/Settings.

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Posterization
Loss of colour resolution when adjusting an image.  The image lands up with patches of uniform colour instead of continuously varying colour gradients.

In an RGB image the colour is represented as a triple (red, green, blue) where each element varies from 0 (black) to 255 (full colour).  If you make several adjustments directly on an image you will get progressively less colour resolution.

For example, when darkening the red component all pixels that had red values ranging from 30 to 37 might be replaced with the value 25.  If you subsequently lighten the red component the value 25 might be mapped to the value 35.  You have now lost color resolution as pixels that previously had slightly different values now have the same colour value.  This posterization effect can be easily seen by using the Curves tool (Image/Adjustments/ Curves) and making a radical shift to the curve.

All the operations under the Image/Adjustments menu directly adjust the colour values of an image.  To avoid posterization it is better to not to use them.  Instead use the Adjustment Layers feature in the Layers window.
This transforms the colour values without affecting the source values.  You can change the Adjustment Layer several times (or remove it) without loss of colour resolution.

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RAW Format
A RAW format saves the data exactly as it was captured by the camera’s image sensor.  Instead of the camera processing the image in real time, decisions about white balance, exposure, contrast, sharpness are all left until the image has been loaded onto the photographer’s computer.  This means that the photographer has finer control over the settings and can alter them if required.

Should club photographers be using the RAW format? Generally, NO.  For most images, the benefit of using the RAW format is negligible.  Taking into account the disadvantages of the format, the recommendation for most photographers is to stick with the traditional JPEG format.

But if you are the adventurous type, or find that for particular types of image you need better image quality, then read on...

The type of sensor used varies from camera to camera, and consequently there are a multitude of RAW formats.  For example, some cameras have more pixels to record the red and green colors than blue (as human perception is less tuned to blue than to red and green).  Also cameras vary in the numbers of bits (8, 10 or 12) that they use to record each pixel.

Because of the number of RAW formats, most computer software cannot process RAW files.  To solve this problem, the camera manufacturers supply software that can convert RAW files to TIFF or JPEG files.  This software can also be used to manipulate images but it is not as powerful as Photoshop, so for precise digital work it is advisable to convert the RAW format to a TIFF file (16 bit) that you load into Photoshop.

You might adjust the white balance using the manufacture’s software (since it is more convenient than Photoshop), but apart from that, it is advisable to leave any other adjustments to Photoshop.  Do not use the manufacturer’s sharpening tool since it does not give you precise control, and will destroy pixel information.

If your cameras records more than 8 bits in the RAW format, you can get greater detail in the dark and light areas of your picture.  You should convert the file to a 16 bit TIFF file and use Photoshop’s Level and Curve tools to adjust the image to your satisfaction before converting it to an 8 bit format (Image/Mode/8 bits per channel).  This (and better sharpening) are possibly the biggest advantages of using the RAW format.

Photoshop CS has a plug-in that can recognize some of the RAW formats, so that you can directly open a RAW file, but Adobe struggles to keep up with the multitude of formats.
You might have to upgrade to Photoshop CS2 and download the latest plug-in from www.adobe.com to get Photoshop to recognize your camera’s RAW format.

RAW files take up more space (about 3 times) than high quality JPEG files.  If you use the RAW format, you should ensure that you have adequate recording capacity (or the ability to frequently download you images from the camera).

Some cameras can record images in both the JPEG and RAW formats.  This uses up even more memory capacity!  If you use the RAW format it is better to record in RAW format only.  If you need quick and dirty JPEG equivalents, you can always use batch processing on your computer to convert the images to JPEG.

Data cannot be written to memory sticks and compact flash cards very quickly.  For this reason cameras have an internal buffer to store images that are taken in quick succession.  The maximum burst rate (i.e. the number of images that can be shot before the internal buffer becomes full) is less for RAW images than for JPEG images since RAW images take up more space.  If you take action pictures and need the additional quality that the RAW format provides, you should buy faster memory.

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Sharpening Images
Use Filter/Sharpen/Unsharp Mask to sharpen an image.  Always view the image at 100% to see the effect of sharpening.

Sharpening changes the pixels in a layer, it is advisable to duplicate the layer before sharpening.  Then you will be able to redo the sharpening if you are unhappy with how the sharpening looks later on.

Excessive sharpening can sometimes result in an unattractive halo around parts of the image.  Yet you might need to apply more sharpening to other parts of the image.  For example, in bird photography applying enough sharpening to get the feather detail right results in a halo around the outline of the bird.  One method that works well is to duplicate the layer, sharpen the top layer to get the feather detail correct, and then apply the Eraser to remove the portions in the top image that are too sharp.

When working in RGB mode, Unsharp Mask can sometimes make saturated colours too saturated.  To avoid this, convert the image to Lab colour (Image/Mode/Lab Colour).  Lab colour has three channels, ‘Lightness’ controlling the tone, and ‘a’ and ‘b’ controlling the colour.  If you select the Lightness channel (shown in the Channels tab of the Layers window) and sharpen it you will not affect the colours.  Bear in mind that converting from RGB to Lab and back again reduces quality.  Also the conversion affects all layers so it does not help to duplicate a layer before converting.  So if you use this technique, do it once in step 6 of the Workflow.

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White Balance
Digital cameras (and videos) can adjust the colour of an image to remove colour casts.  So an image lit with tungsten light, which gives a yellow cast, can be adjusted by the camera to look as if it was taken in daylight.  The same image taken with film (daylight balanced) will appear yellow.

Automatic white balance (AWB) is often useful, but the camera can get it wrong and can sometimes be counter-productive.  If you take a picture because of the mood of the ambient light, you will be distressed to find that the camera has removed or reduced the effect!

The solution is to think about why you are taking the picture.  If you are taking it for the colour effect use the LCD screen on the camera to check if the image is satisfactory.  Since AWB is applied separately to each image you unfortunately have to check each one.  If the picture has some natural white in it the AWB is likely to work correctly.  So a landscape with some cloud in it might work, while the next landscape without cloud might not.

If AWB does not work properly, most cameras have white balance modes were you tell the camera if you are shooting in bright sunlight, shade, tungsten lighting etc.

If you need accurate color rendition it is best to use the Custom White Balance feature [Canon terminology – not sure what Nikon terminology is].  To calibrate the custom white balance you photograph a white image or a gray card, so the camera knows what a neutral colour looks like.  It can then adjust for the colour cast in the subsequent pictures.  Accurate colour rendition is normally not important in club photography.  For most pictures it is the effect of the colour rather than colour accuracy that counts.  Even in categories such as wildlife and photojournalism it is sufficient to ensure that the colours are approximately correct.

Digital workers (unlike slide workers) can adjust the colour balance of their images afterwards to get the exact effect that they want.  In Photoshop use the Colour Balance, or use the Gray Point and White Point eye-droppers in Levels. But remember to use adjustment layers to avoid Posterization.  Some posterization will occur if camera adjusts the white balance and you subsequently reverse the effect in Photoshop.  So it is better to ensure that the white balance adjustment made by the camera is roughly correct.  (Using RAW mode it is possible to import pictures from a camera and adjust the white balance with the absolute minimum of posterization.  But this process involves more work and generally does not improve the quality significantly.)

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Workflow
[This is written based on Canon terminology.  If you have experience with Nikon (or other brands) and their terminology is different please let Des Currin know so that he can make this guide relevant to those brands as well.]

Workflow refers to the steps used to process images.  Some of the choices given here are subjective, so you might prefer to do it a differently.  But if you are new to digital photography and bewildered try this approach until you have built up some experience.

If you make changes to your workflow consider the following goals: It should;

  • Be efficient to operate.  This is particularly important at the front end (steps 1-3) where you are processing many images.  For example, cataloging systems where enter keywords for every image are too time consuming for home use.
  • Maintain flexibility.  If you decide to make changes to an image, you should not have to redo all of the steps for that image.
  • Support multiple uses of an image.  You should not submit the same image to the club in more than one division (e.g. print & digital), but you might want to e-mail the image to friends, make a print to put on your wall, include the image in an audio-visual, or use parts of an image in a montage.
  • Maintain the quality of an image.  Multiple edits if done incorrectly can severely reduce the quality of an image.
  • Allow you to identify the original image.
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1. Take the pictures (this is the fun bit)

  • It is recommended that you set up your camera to save the pictures as JPEG in sRGB mode.  (Later on you might want to consider using the Adobe RGB or RAW modes.)
  • Use the highest image size (normally called Large) and quality (normally called Fine).
  • Check the file numbering system on your camera.  You want to ensure that each image will be assigned a unique number.  Canon refers to this as Continuous.
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2. Import the pictures onto the computer

  • The images will be saved with a JPG extension.
  • Set up the import to create a separate directory for each shooting date (i.e. the date the pictures were taken on).
  • If two or more people are sharing the same computer, but each only has one camera, use separate directories for each person.  Use separate directories in the subsequent steps of the workflow so that your images don’t get mixed up.
  • If you use multiple cameras keep separate directories for each camera, and rename the files with a unique prefix after they have been downloaded so that the images from each camera cannot get confused.
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3. Throw out the duffs and identify the gems

  • Use the slideshow feature to quickly view all the images.  This shows which pictures have the most impact, and where you have got similar pictures.
  • Go through the pictures one by one and delete the duffs and duplicates. If a picture is displayed in a small size it looks sharper than it actually is.  So always examine the pictures at 100% size before deciding whether they are sharp (I once made the mistake of deleting a picture because there was a similar one with better composition and then realized that the remaining one was not sharp).
  • Remember that you can crop and adjust the exposure and colour balance later, so do not throw out pictures because they have some flaws ‘as presented’.
  • Don’t be too heavy handed.  Keep images even if they are not suitable for club.  There is a life outside of club photography and you will enjoy showing them to family and friends at a later point.
  • If your software has a star rating system, it can be useful to mark the duffs with a 1 star, and then select them and delete them in one batch.
  • Identify the gems and mark them with the highest star rating.
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4. Copy your gems to a ‘Club Source Files’ directory.

  • Keep the same file names as the original files.
  • Later when you have time and inspiration you can browse through this directory to find images to work on.
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5. Editing an image

  • Volumes can be written (and have been written) about editing in Photoshop.  In this step we simply suggest what you need to do to maintain the quality of the image and retain the flexibility to change the image later on.
  • Load the image into Photoshop and immediately save it in the ‘Club Source Files’ directory with the same name but as a Photoshop file (this has a PSD extension).
  • The PSD format allows you to save a file multiple times without losing quality (unlike JPEG).
  • Use adjustment layers to make changes to the picture rather than changing the contents of a layer.  This gives you the flexibility so that you can change things like exposure later on without losing quality.  There are adjustment layers for many common operations (e.g. Levels, Curves, Color Balance, Contrast, Saturation).
  • If you need to change the contents of a layer (e.g. sharpening or using the clone tool) duplicate the layer before you start.  This allows you to reverse the effect later on.  By changing the opacity of the top layer you can easily adjust the strength of the effect.
  • The beauty of Photoshop is that you can work easily with multiple layers.  Do not flatten the layers (i.e. merge them into one) in this step.
  • Avoid resampling your image (this is a checkbox in Image Size) in this step.  Resampling changes the number of pixels in the image (normally it is a reduction).  Since it affects all layers it does not help to duplicate the layer.
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For example, you might want to use an image as a print and for digital projection.  Prints need a high pixel resolution.  At a resolution of 300 pixels/inch, a 15x10 inch print requires 4500x3000 pixels.  In contrast for digital projection you need to reduce the number of pixels down to 1024x768.  If you resample down to 1024x768 without first saving a copy of the file you are not going to be able to make a print.  Resampling is best left to step 6.

  • Cropping a picture also discards pixels but it is normally an action you can take early on in the editing process without regret.  If there is more than one way to crop and you are not sure which will be better, defer the cropping decision until later.  If need be, save a copy of the file.
  • Save the final PSD file (without flattening).  You would normally use the same filename as the original file.  If you have combined several images the filename could include the numbers of all the original images.
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6. Producing final output

  • Use Image Size to resize (change the physical dimensions) and resample (change the number of pixels) to get the size output you require.
  • The physical dimension and resolution are important for print work.  You need a resolution of 200-300 pixels/inch for prints.
  • For digital projection you only need to worry about the pixel dimensions (max 1024x768).
  • Sharpen the image to your satisfaction (Filter/Sharpen/Unsharp mask) and examine it at 100% to see if there are any problems.  To get a good impression of the whole image view it at 50%, 25% or 12.5%.  Don’t use non-even fractions like 33% as it can distort the apparent sharpness of the image.
  • Do not save over the PSD file created in step 5.
  • It is okay to save over the JPEG file copied into the ‘Club Source Files’ directory in step 4 since you should still have the file created in step 2 in the original directory.
  • For digital projection, save the file as a JPEG file with the highest image quality.  This will normally result in a file less of less than 1 Megabyte (the limit for club use).  If the file size is too large choose a slightly lower image quality.
  • For print work save the file as a TIFF file or as a JPEG file.  The quality of TIFF is slightly better than JPEG, but some print shops don’t accept TIFF (notably shops using Frontier machines).  If you save it as a JPEG file make sure you don’t overwrite the JPEG you might have created for digital projection (if necessary add a P to the filename to show it is the print version).
  • When you are done, move all the files (PSD,JPEG,TIFF) from the ‘Club Source Files’ to a ‘New For Club’ directory.  This ensures that the ‘Club Source Files’ directory only contains images that still need to be worked on.
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7. Selecting images for club night

  • Overtime you will land up with several images in the ‘New For Club’ directory.
  • It is a good idea to let some time elapse between steps 6 and 7.  This is so that the passion generated while working on the image in step 6 can be tempered with a more objective view of the image.
  • It helps a lot to view all the images in the ‘New For Club’ directory so that you can compare the quality of the various images and make the selection.
  • As any competitive club photographer knows there is an art to deciding which images to put into club:
  • If you are about to complete a rating level, say two star, you want to use up the images that are good enough for that level but unlikely to be successful in the next level.
  • You don’t want to put similar images in on a night as it reduces the impact.
  • In the higher rating levels you need to get a variety of categories.  In some cases an image may qualify in more than one category.  So you put the image in the category where you have the least golds.
  • Alternatively you can take a more relaxed approach to the selection process.
  • Move all the files that you have selected for club into a new directory (say ‘Club yyyy-mm-dd).  This includes all the variants (PSD, TIFF, JPEG).
  • If you are submitting for digital projection rename the JPEG version so it is in the following format: s_ccc_ttttt_nnn_ooooo.jpg
    s star rating (1-5)
    ccc first three letters of category in lower case (e.g. spo=Sport)
    ttttt title (max 24 characters)
    nnn author’s number (ask Des Currin or Lyneth Crighton for your number)
    ooooo author can use this to identify the original image.

The last part (ooooo) can be as long as necessary and should identify the filename of the equivalent PSD file.  For example 3_pic_Setting sun_555_1642.jpg

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8. After club judging

  • If your images got rave reviews at the club you should copy all variants of the image (PSD, TIFF, JPEG) into a ‘Best of the Best’ directory.
  • You will use this directory in the future when you want to select images for trophy night, salons, PSSA panels etc.
  • You might choose to include an image in the ‘Best of the Best’ directory in spite of a poor reception at club.  Judges are fallible, so go with your instincts.
  • You can always go though the ‘Best of the Best’ directory at a later stage and clean out the marginal images.
  • It is easy to make copies of files, so it can be useful to create specialized directories for categories such as ‘Lions’.  Make copies of all your good lion images in this directory.  After accumulating images for a number of years you will find that you have a number of similar images.  You can then delete the weaker images so that you are left with a very strong collection.

Make regular backups of your files.  Workflow means nothing if you loose your data...

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