Basic Photo Theory and Digital Workflow (4 of 4)
Assuming that we have taken a number of photographs, which are saved on your camera's memory card, we now need to transfer our images onto our computer, to allow us to edit and tweak them until we are happy with a final result. This 'out of camera' adjustment stage is known as post-processing. The amount of adjustments we make are dependant on what file format we have shot in, what the final image use will be, and whether we want a 'true' photograph or create a piece of 'photoart' by applying various art effects.
Camera images can be transferred to your computer by either removing the memory card from your camera and placing it in a card reader or card slot connected to your computer, or by connecting a USB cable from your camera to your computer. Usually when you use a USB cable, your computer will automatically detect the camera, and autorun a file transfer program that is associated with your camera. eg with a Nikon camera, a connection will run Nikon Transfer, if installed.
Once you have your images transferred onto your computer, you'll have to decide what graphics application you want to use for your photo-editing. A great many people use Adobe's Photoshop program, which is excellent but expensive. I have for many years used Corel's (previously JASC) Paint Shop Pro, which can achieve everything I require at a fraction of the cost, and allows me to create scripts which emulate many traditional darkroom techniques.
Before we get started though, an important step to take is to look through all the images you've just transferred, and make a 'keep or delete' decison for each image. The beauty of digital photography is that you can take as many shots as there is space on your memory card, but you don't necessarily want to keep every one. You should therefore take some time to decide which 'less than perfect' shots to delete, only keeping the images you are satisfied with. Zooming in to check peoples eyes, or background detail & distractions often helps.
As mentioned in a previous chapter, if you have decided to shoot in RAW mode, there is an intermediate and important stage in the post-processing workflow required, where we adjust sharpness, exposure compensation, colour balance etc before saving the image in a standard file format (Tiff, Jpeg) for any further final work to the image in your graphics program.
If you load your RAW file directly into your graphics app, and it supports RAW, a dialog box should appear, allowing you to make any RAW tweaks to the image. In Adobe Photoshop (and Lightroom)for instance, the dialog that is used is known as ACR (Adobe Camera Raw), and acts as a 'go-between', converting the raw image data into a known image format that Photoshop can use. Paint Shop Pro uses a similar interface to load RAW images, although it has to be said, less effectively. However, the very best way to get all the detail and resolution from your RAW images, is to use your camera's own brand of dedicated RAW conversion software. For instance, in Nikon's case, this is Nikon Capture NX. This ensures the true fidelity of your image as it uses the same software as that embedded in your camera.
Other third party RAW conversion applications such as Lightroom, CaptureOne, DxO and Bibble are also worth investigating to see which interface suits you.
RAW images as they come out of the camera, are by their very nature unprocessed. So it may be surprising that they require at the very least some sharpening, and you may want to adjust certain other aspects of the original shot such as exposure compensation. This is where shooting in RAW really comes into its own. It allows the photographer a huge amount of flexibility over the final outcome of images, by altering these settings while the image is still in a raw data state, as if altering settings on the camera whilst taking a shot.
As sharpness is a routine adjustment required, it is important that the amount of sharpening you make is suitable. It's very easy to over-sharpen an image, losing true resolution and creating noise. It's best to use the Unsharpen tool, starting with low values. For instance, using Nikon Capture NX on a D300 RAW image, the Unsharpen values I would use are Intensity 50, Radius 5, Threshold 4. This will vary between cameras and software, but is a useful starting point.
Other tweaks that are best made with your RAW conversion software is White Balance, Histogram Adjustment and Exposure Compensation. Altering White Balance settings can erradicate colour casts created by various light sources, and you can also usually select a grey point using a dropper tool to 'normalize' your image's white balance. Histogram adjustments affect the overall dynamic range of your image. Although modern sensors are very good at capturing this correctly, you may often see flatline sections at the edge of your histogram, particularly to the right. Pulling the slider in to where the histogram drops down to the baseline will clip the histogram and give your image a truer luminance.
Exposure Compensation is sometimes required, particularly when there has been difficult lighting conditions. Minor adjustments may be required to your own taste. This is an adjustment that can ONLY be made accurately when working on your RAW file. Once the file has been saved into another format, you can only adjust brightness/lightness/contrast to emulate exposure compensation, which is never as effective.
Only when you're sure that you've adjusted all levels as required to you satisfaction, do you save the image as a Tiff, Jpeg or other format, thus locking in your image's base configuration settings. You'll always have the original RAW file as your digital negative, so be sure you don't overwrite it with a tweaked version. I would recommend saving your file at this stage as a Tiff (without compression), as it will retain the highest resolution for either printing or further adjustments.
Although RAW conversion adjustments can be time consuming, standard adjustments on a folder of similar images can be processed using 'batch processing' available as an option with most software.
Once you have edited and saved your RAW converted image file, or have only shot in Jpeg or Tiff mode, you can make any final alterations to your standard image file in your graphics application. If you originally shot in Jpeg or Tiff, you may want to check your image's sharpness, although your camera, in non-RAW mode, applies some sharpening as part of its custom settings, depending on your menu values.
Most graphics applications will also allow you to check and adjust your image's histogram settings.
Other important adjustments to make are checking for level horizons, cropping and removal of unwanted distractions. A sloping horizon can be very distracting, but can be easily corrected using the image rotate tool. It's best to first switch on the grid overlay so you can see how much adjustment has to be made, then make small rotation adjustments until the horizon looks straight against the grid. Once you have it right, you will have to crop the image slightly to trim back to straight edges.
Cropping, and knowing what and how much to crop, is a very important stage in the whole process, and can be as important as the original composition decisions made when taking the shot. Some images will not require any (or very little) cropping, depending on how well the original shot was composed in the viewfinder. Others may be fine images, but may require fine tuning to crop down the image to make a better composition, or through cropping, bring the subject into a Rule of Thirds position (as mentioned earlier). This can be checked during cropping in Paint Shop Pro by using my PSP Rule of Thirds script. It's often interesting spending some time considering different crops within an image, as various compositions can be had from a single image through different crops of the original.
It's also worthwhile getting acquainted with the Clone tool, as it allows you to remove or 'disguise' small distractions in your image, such as some debris or an unwanted mark. This is a similar technique to the traditional 'spotting' work you would do on old prints, but allows a huge amount of extra sophistication, as you can copy material from one part of the image (or another image!) and blend it into another section to cover any blemishes. You can also tone down bright objects using partial opacity (as well as using contrast and darkening tools).
Other useful tools that are available in some graphics applications are 'Auto Curves' & 'Auto Levels', which will automatically make adjustments to histogram, contrast, luminance, saturation etc, and can often make significant improvements to your photographs, although, with the right care when taking your shot and RAW conversion, the improvements may become minimal, often best adjusted manually once you become more experienced.
There are many other artistic tools and procedures you can use to further enhance your images, or turn them into photo-artwork. However, the above details the basic steps required to process your photographs to a reasonably finalised state. It's up to you how much time and effort you are prepared to spend on each stage, to get the very best out of your work. I hope the above and previous information proves useful as a template for your own digital workflow.
Post-Processing
Camera images can be transferred to your computer by either removing the memory card from your camera and placing it in a card reader or card slot connected to your computer, or by connecting a USB cable from your camera to your computer. Usually when you use a USB cable, your computer will automatically detect the camera, and autorun a file transfer program that is associated with your camera. eg with a Nikon camera, a connection will run Nikon Transfer, if installed.
Once you have your images transferred onto your computer, you'll have to decide what graphics application you want to use for your photo-editing. A great many people use Adobe's Photoshop program, which is excellent but expensive. I have for many years used Corel's (previously JASC) Paint Shop Pro, which can achieve everything I require at a fraction of the cost, and allows me to create scripts which emulate many traditional darkroom techniques.
Before we get started though, an important step to take is to look through all the images you've just transferred, and make a 'keep or delete' decison for each image. The beauty of digital photography is that you can take as many shots as there is space on your memory card, but you don't necessarily want to keep every one. You should therefore take some time to decide which 'less than perfect' shots to delete, only keeping the images you are satisfied with. Zooming in to check peoples eyes, or background detail & distractions often helps.
RAW Conversion
As mentioned in a previous chapter, if you have decided to shoot in RAW mode, there is an intermediate and important stage in the post-processing workflow required, where we adjust sharpness, exposure compensation, colour balance etc before saving the image in a standard file format (Tiff, Jpeg) for any further final work to the image in your graphics program.
If you load your RAW file directly into your graphics app, and it supports RAW, a dialog box should appear, allowing you to make any RAW tweaks to the image. In Adobe Photoshop (and Lightroom)for instance, the dialog that is used is known as ACR (Adobe Camera Raw), and acts as a 'go-between', converting the raw image data into a known image format that Photoshop can use. Paint Shop Pro uses a similar interface to load RAW images, although it has to be said, less effectively. However, the very best way to get all the detail and resolution from your RAW images, is to use your camera's own brand of dedicated RAW conversion software. For instance, in Nikon's case, this is Nikon Capture NX. This ensures the true fidelity of your image as it uses the same software as that embedded in your camera.
Other third party RAW conversion applications such as Lightroom, CaptureOne, DxO and Bibble are also worth investigating to see which interface suits you.
RAW images as they come out of the camera, are by their very nature unprocessed. So it may be surprising that they require at the very least some sharpening, and you may want to adjust certain other aspects of the original shot such as exposure compensation. This is where shooting in RAW really comes into its own. It allows the photographer a huge amount of flexibility over the final outcome of images, by altering these settings while the image is still in a raw data state, as if altering settings on the camera whilst taking a shot.
As sharpness is a routine adjustment required, it is important that the amount of sharpening you make is suitable. It's very easy to over-sharpen an image, losing true resolution and creating noise. It's best to use the Unsharpen tool, starting with low values. For instance, using Nikon Capture NX on a D300 RAW image, the Unsharpen values I would use are Intensity 50, Radius 5, Threshold 4. This will vary between cameras and software, but is a useful starting point.
Other tweaks that are best made with your RAW conversion software is White Balance, Histogram Adjustment and Exposure Compensation. Altering White Balance settings can erradicate colour casts created by various light sources, and you can also usually select a grey point using a dropper tool to 'normalize' your image's white balance. Histogram adjustments affect the overall dynamic range of your image. Although modern sensors are very good at capturing this correctly, you may often see flatline sections at the edge of your histogram, particularly to the right. Pulling the slider in to where the histogram drops down to the baseline will clip the histogram and give your image a truer luminance.
Exposure Compensation is sometimes required, particularly when there has been difficult lighting conditions. Minor adjustments may be required to your own taste. This is an adjustment that can ONLY be made accurately when working on your RAW file. Once the file has been saved into another format, you can only adjust brightness/lightness/contrast to emulate exposure compensation, which is never as effective.
Only when you're sure that you've adjusted all levels as required to you satisfaction, do you save the image as a Tiff, Jpeg or other format, thus locking in your image's base configuration settings. You'll always have the original RAW file as your digital negative, so be sure you don't overwrite it with a tweaked version. I would recommend saving your file at this stage as a Tiff (without compression), as it will retain the highest resolution for either printing or further adjustments.
Although RAW conversion adjustments can be time consuming, standard adjustments on a folder of similar images can be processed using 'batch processing' available as an option with most software.
Non-RAW post-processing
Once you have edited and saved your RAW converted image file, or have only shot in Jpeg or Tiff mode, you can make any final alterations to your standard image file in your graphics application. If you originally shot in Jpeg or Tiff, you may want to check your image's sharpness, although your camera, in non-RAW mode, applies some sharpening as part of its custom settings, depending on your menu values.
Most graphics applications will also allow you to check and adjust your image's histogram settings.
Other important adjustments to make are checking for level horizons, cropping and removal of unwanted distractions. A sloping horizon can be very distracting, but can be easily corrected using the image rotate tool. It's best to first switch on the grid overlay so you can see how much adjustment has to be made, then make small rotation adjustments until the horizon looks straight against the grid. Once you have it right, you will have to crop the image slightly to trim back to straight edges.
Cropping, and knowing what and how much to crop, is a very important stage in the whole process, and can be as important as the original composition decisions made when taking the shot. Some images will not require any (or very little) cropping, depending on how well the original shot was composed in the viewfinder. Others may be fine images, but may require fine tuning to crop down the image to make a better composition, or through cropping, bring the subject into a Rule of Thirds position (as mentioned earlier). This can be checked during cropping in Paint Shop Pro by using my PSP Rule of Thirds script. It's often interesting spending some time considering different crops within an image, as various compositions can be had from a single image through different crops of the original.
It's also worthwhile getting acquainted with the Clone tool, as it allows you to remove or 'disguise' small distractions in your image, such as some debris or an unwanted mark. This is a similar technique to the traditional 'spotting' work you would do on old prints, but allows a huge amount of extra sophistication, as you can copy material from one part of the image (or another image!) and blend it into another section to cover any blemishes. You can also tone down bright objects using partial opacity (as well as using contrast and darkening tools).
Other useful tools that are available in some graphics applications are 'Auto Curves' & 'Auto Levels', which will automatically make adjustments to histogram, contrast, luminance, saturation etc, and can often make significant improvements to your photographs, although, with the right care when taking your shot and RAW conversion, the improvements may become minimal, often best adjusted manually once you become more experienced.
There are many other artistic tools and procedures you can use to further enhance your images, or turn them into photo-artwork. However, the above details the basic steps required to process your photographs to a reasonably finalised state. It's up to you how much time and effort you are prepared to spend on each stage, to get the very best out of your work. I hope the above and previous information proves useful as a template for your own digital workflow.
Posted by Howard Dickson
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Further reading...
- Epic Edits
- Landscape Photography
- Outback Photo