Section 3.2. Process Stage


3.1. Input Stage

The ability to implement consistency has been enhanced by the advent of color management, but it's still a challenge. Within the three stages of a digital workflow, the most challenging stage in which to maintain consistency is the input stage because the types of input vary so widely.

Input can come from three main sources: scanners, digital cameras, or digital files supplied by someone else. Each type of input brings its own challenges with regard to maintaining consistency.

3.1.1. Scanned Input

Scanner input variation arises from the different substrates you might want to scan. Transparency film, negative film, prints, and flat art comprise most scanning workflows, and each has different parameters to consider.

Whether you're using drum scanners, dedicated film scanners, or flatbed scanners, scanning technology has improved dramatically in recent years, allowing for faster and easier scanning workflows, with better color and tonality and the incorporation of color management. These advancements are mostly due to improvements in software and driver interfaces along with higher-quality sensors.

Resolution, color, tonality highlight and shadow, sharpening, bit depth level, dust, noise, and, of course, color management will all affect your scanning input. Most of these settings can be adjusted within the software or driver interface. Another option is to adjust and correct scans from within Photoshop.

3.1.1.1. Choosing scanning resolution

A good starting point in achieving superb scans is knowing your scanner's optical resolution. If a scanner's optical resolution is 1600 ppi (pixels per inch), you can multiply or divide that by a factor of two to achieve native resolution. Take an optical resolution of 1600, divide by two, and scan at 800. Divide by four and scan at 400. Multiply by two and scan at 3200. All of these are native resolution settings, which are the result of the scanner quickly dividing or multiplying its optical resolution to yield optimum results. If you set this scanner to scan at 1250 ppi, it will scan in this nonnative condition, but this setting will create two critical workflow bottlenecks:

  • The scanner speed will slow down because it must interpolate the data.

  • The nonnative scan will yield a lower-quality pixel integrity.

Most scanner driver interface options show resolution settings in a pull-down menu, and the native resolutions are usually bold or underlined.


Scan for the final output (print size and resolution) whenever possible. It is best to scan at the native resolution nearest the resolution or file size that you need. For instance, if you are scanning to produce an 8 x 10 print on a device that requires 250 ppi (pixels per inch) resolution, you will produce a file nearly 14MB in size. To produce a 16 x 20 print at a resolution of 200 ppi, the file size will be close to 37MB. (Both of these measurements are in RGB 8-bit). In Photoshop, under File New, you can type in inch and resolution settings and learn the file size you need for output. In the scanner interface, choose the resolution that scans close to your target file size, preferably using native scanner resolution. Once the scan is complete, in Photoshop, using Image Image Size, you can resize the image by resampling to the exact dimensions and resolution, or you can even use the Crop tool with the settings in the Options bar.

If you are scanning for multiple uses, it is best to scan to the largest size and then resample the image to make it smaller in Photoshop.


3.1.1.2. Leveraging the scanner's software

Some scanners include software that is extremely limited, while others offer full-featured software, allowing you to scan with many excellent tools. Some software gives you the option to scan in different modes, ranging from totally automatic to expert manual. If your scanner's software is not adequate for accurately controlling the scanner, you have the option of either purchasing a scanner that allows more control or acquiring third-party software. Good software properly used will allow you to preview a scan on your monitor with accurate color and tonality. You might have the ability to improve the image by adjusting the highlight and shadow, color, and tonality. If your scanning software does not allow for accurate color or is limited in controls, it may be best to scan your images with the default settings and then make adjustments in Photoshop. Be careful with default settings that are automatic, because in most cases the automatic settings can lose detail in both the highlights and shadows. This is the case if you open a scan in Photoshop, because the scanning interface does not use the monitor profile for viewing, which Photoshop does automatically.

Most scanning software includes advanced settings or preferences, including color management settings for input, monitor, and RGB and CMYK ICC profiles. Using custom or factory input profiles for the scanner will assist you in matching the image that you are scanning.

However, scanning negative film may require a lookup table (LUT) of predetermined characteristics because the film base, usually orange in color, must be compensated for during scanning. While using a custom input ICC profile for negative film is a wonderful solution, these profiles are very difficult to create and are not easy to come by. The next best solution is to use a negative LUT for a particular type of film.

3.1.1.3. Starting with high bit depth

Scanners have a bit-depth level of either 8 or 16 bits per channel. More bits means more tonal information. An 8-bit image has 256 tones per channel, and a 16-bit file has 65,536 tones per channel. A 16-bit scan yields a fantastic amount of tonal information, which is useful for editing without degrading the image. When you apply a profile to a scan, it is better to start with a high-bit scan. Also, if you plan to do some major editing in image-editing software such as Photoshop, the extra tonal information will help a great deal in preventing posterization or banding.

3.1.1.4. Avoiding dust and noise

Start with the best image possible by cleaning your glass, slides, negatives, and flat art carefully before scanning, using only recommended methods from the scanner manufacturer. Higher-end scanners, especially at greater resolutions, show more dust than less expensive scanners at lower resolutions. Dust is always a problem, especially with flatbed or film scanners. Drum scanners minimize this problem if the source image is oil mounted by applying a liquid film over the actual film. You can also oil mount film on flatbed scanners. Some scanners use Digital ICE, an amazing software technology that will minimize dust when scanning. However, when you use such an option, the scanner will take much longer to scan, and the final result may not be as sharp as it would be otherwise.

Noise from a scan can be caused by high ISO film speeds, underexposure, pushing film speed during processing, and by heat in the scanning device itself. With the exception of drum scanners, scanners introduce noise in the shadow areas of transparencies because the dynamic range of the scanner is smaller than the dynamic range of the film. Transparency film can have a density range of up to 4.0, while the density range of most non-drum scanners is around 2.9, thus creating noise in the dark shadow regions. However, drum scanners have the ability to pull detail from shadow regions of transparencies with little or no noise.

3.1.1.5. Scanning halftones

When scanning a page from a magazine, book, or anything that has halftone dots, a descreening option in the scanner interface will reduce this pattern but result in a softer image.

In the production-techniques-oriented books in this series, I will cover a scanner dust-spotting technique that uses Photoshop's History brush to minimize dust spots very quickly, leaving a high level of sharpness and pixel quality. I'll also discuss other techniques in Photoshop to minimize digital noise.


Sharpening is best kept to the last step in the process before outputting the image, and unless you're scanning for direct printing (bypassing other processing options in Photoshop), I recommend scanning with no or little sharpening settings from the scanner, thus ensuring expanded pixel data.

Scanners will be around for a long time to come because we not only have prints and flat art to scan, but billions of negatives, transparencies, and artifacts that are stored for the future using scanning technology.


3.1.2. Input from Digital Cameras

Digital capture has brought enthusiasm to the digital workflow because it allows you to create the image in the camera, process it in Photoshop, and then send the file to the lab or digital printer within minutes, if necessary. It is also possible to capture an image and send the file to a printer directly (as many event photographers do on-site), and there is even the option of wirelessly transferring images to your computer as you're shooting. When a digital camera is providing input, you're faced with keeping things such as white balance and exposure consistent under changing lighting and environmental conditions.

3.1.2.1. Digital camera input and resolution

Compared to a scanning workflow, in which you can scan to the size of the file (or the resolution) needed for a particular output, digital camera resolution is for the most part determined by the camera's available megapixels. Mega (meaning one million) pixels (meaning a light-sensitive photon) are set to a particular size during capture. So a 12-megapixel camera yields 12 million tiny photons on a sensor that becomes what we referred to in a film workflow as the "latent image" after the exposure.

Once you process a 12-megapixel file, the converstion to RGB will cause the file to become three times larger, thus yielding a 36MB RGB file.


In your workflow, this 36MB file would be considered the original file resolution. You can resample the image with Photoshop or a third-party resampling software/plug-in to make it larger or smaller. If you're working with RAW files, you can resample from Adobe Camera RAW or another RAW software interface. At this point in your workflow, the most important factors for resolution are proper white balancing and proper exposure of the original capture because a healthy original file can yield bigger and better quality output. It's more forgiving.

When you're shooting in JPEG (or TIFF) format, the camera processes the image as an 8-bit file. When shooting in RAW format, you can process the file into an 8-bit or 16-bit image along with controls for white balance, color, sharpness, contrast, brightness, exposure, and more to create a healthy original file.

DIGITAL IMAGE SENSORS (CMOS VERSUS CCD)

There are two types of digital image sensors: CMOS (Complementary Metal Oxide Semiconductor) and CCD (Charged-Coupled Device). The majority of SLR digital cameras today employ CCD sensors. However, as the technology of CMOS sensors improves, digital cameras will use these new chips. Some manufacturers are already using CMOS sensors in their digital cameras, and the quality is excellent. The primary practical difference is that a CCD chip may require more of a controlled temperature and more electrical power, thus requiring more battery use, but it yields a sharper file initially. The CMOS sensor requires less battery power, has a broader range of temperature sensitivity at a given ISO setting, is less contrasty, and produces less digital noise at higher ISO settings.

Canon EOS 1Ds Mark II full-frame CMOS chip


Think of shooting JPEG as creating a color transparency in which proper exposure is critical, whereas shooting RAW can be compared to shooting a color negativeexposure is certainly critical, but the exposure controls in the RAW process have a greater latitude.

One of the main challenges of digital capture is getting the color and exposure right from the start, which will not only save time in production, but will ensure the very best output quality.


3.1.2.2. Establishing white balance

Specialized imaging devices allow you to capture a light spectrum that includes everything from X-rays to infrared light, but we're interested only in the part of the spectrum that is visible to the human eye. Visible light has a color temperature that is measured in degrees Kelvin. The higher the number the bluer the image, while the lower the color temperature, the yellower the image. We refer to visible-light color temperatures as daylight, tungsten, fluorescent, and so on, each having a different Kelvin degree temperature. Daylight is considered to be approximately 6500K and tungsten light 3200K. However, the color temperature of daylight varies a great deal depending on the time of day, season, and altitude. Our eyes adjust to these changes, but cameras take things a little more literally. Because these variations will change color perception in general, white balancing will become an important part of your workflow.

There are three primary options for white-balancing digital cameras:


Auto

Although auto works extremely well in many conditions, it can potentially generate a different color temperature from one image to another, which is important to keep in mind when you need to implement consistency. While an image may look great by itself, it may require individual adjustments to look consistent with other images if it is going to appear in a book, presentation, or montage.


Preset

The presets for white balancing that come with most digital cameras let you choose a specific color temperature, such as daylight, tungsten, shade, fluorescent, cloudy, flash, or even a dial-in. Using a preset white balance may allow more consistent color among images in a given lighting environment, and if you need to make adjustments, they can easily be applied to an entire set of images.


Custom

Custom white balancing allows the camera to balance the color temperature more accurately, taking in not only the primary light source itself but surrounding elements that may influence the color temperature (such as green grass, red brick, or blue sky). Custom will also white balance the camera to a light source other than one of the presets. Tools for white balancing a digital camera include a reflective readingsuch as a digital gray card, white card, or a non-color bias (neutral) reference that you can use to create an exposure of the reference (gray card) in your scene, or an incident reading, such as the ExpoDisc that fits to the front of the lens, allowing you to create an exposure of the light coming toward your subject.

Regardless, once you have your white balance exposure, there are two provisions to set on your camera. First, set the camera's white balance function icon to "custom" (check your reference manual if you need to), and second, in the camera menu, select Custom White Balancing. This will allow you to select an image to use as the source. Select the image, and then select Set or OK. You are now shooting with a custom white balance since the camera has balanced the color temperature to your specific lighting conditions.

Use a custom white balance whenever possible, especially when photographing a series of images in an environment that has fast-changing lighting conditions. Learn to quickly switch your white balance to either a preset or saved custom setting to keep your color as consistent as possible.

3.1.2.3. Exposure

Exposure control is perhaps the single most important factor to most of us when using a digital camera, and it is certainly the best way to ensure detail in both the shadow and highlight regions, not to mention the best way for color management to work seamlessly through the process.

Some people can look at any scene, consider all the elements, and determine the correct exposure with the blink of an eye; experience is the best teacher when it comes to getting a proper exposure. In the meantime, you'll need to employ the tools availablein-camera metering, the preview histogram, Exposure Mode, exposure compensation, and custom camera functions, along with a professional handheld exposure meterto help you achieve proper exposure.

Once an area is grossly overexposed using a digital camera, the only means to regain detail is to rebuild the texture using advanced rebuild techniques that we'll cover in the Advanced Production Techniques book.


Become familiar with the various shooting modes for your camera, such as Program (P), Shutter-Priority (Tv), Aperture-Priority (Av), Manual (M), and (B) Bulb, and meet the challenge of becoming proficient with your exposure.

RAW WORKFLOWS

Once again, when it comes to exposure, shooting RAW has many wonderful advantages in today's high-quality digital workflows. RAW allows you to quickly change exposure compensation without sacrificing pixel quality. All digital camera manufactures have software for processing their proprietary RAW file formats, such as Digital Photo Professional from Canon, Nikon Capture Editor from Nikon, and Capture 1 by Phase One, all of which give you the ability to maintain the highest possible pixel quality. There are also other third-party software options for processing RAW files, such as Adobe Camera Raw, Adobe Lightroom, Bibble Pro, and Aperture, that have powerful features for today's digital workflows. This software works with file types such as JPEG and TIFF for individual or batch editing, renaming, and processing. However, these programs are best at processing RAW files, especially in large operations that may have large numbers of RAW files from various different cameras. Having the ability to process and manage all of these files with one application greatly increases productivity.

(Compared to shooting with the much smaller JPEG format, a RAW workflow requires a healthy amount of manageable hard drive space, which we will discuss at the end of this chapter.)


Adobe Lightroom Beta

Adobe Camera RAW

Digital Photo Professional - Canon

WHEN TO SHOOT JPEG?

JPEG workflows are best suited for event photography, photojournalism, public relations, some government agency work, and other types of high-volume workflows in which images need to be uploaded or wirelessly transfered quickly to a printer or via the Internet. When shooting in the JPEG format, you have color space options, such as sRGB or Adobe RGB, which will help create and customize a picture style or "look," that include settings for saturation, contrast, color tone, sharpness, and even filtering or toning effect. These "looks" can represent settings for portrait, product, landscape, or even monochrome.


3.1.2.4. Other considerations with digital cameras

Keeping the digital camera sensor free of dust is extremely important and should become part of your maintenance routine. When you change lenses in the field, such as in a building where there are lots of dust particles, dust can invade the inside of the camera body and find a home on top of the sensor. The dust particles will appear as spots on your image files, usually at the same location on each image, causing a considerable amount of additional retouching time. Some photographers will have several cameras with different lenses, never changing the lens so as to keep sensors free from these intruding particles. Camera stores offer the necessary tools to keep your sensors clean, and some offer a professional sensor-cleaning service.

Keep a close eye out for online firmware updates from your camera manufacturer. These updates expand camera capabilities and offer improvements for certain camera functions. Some camera manufacturers, such as Nikon, require that you send the camera back to the manufacturer for a firmware upgrade; others allow you to simply download a small text file, transfer it to your camera's flash card or microdrive, place the card in your camera, and use the menu on your camera to quickly update the firmware. (In some cases, you can hook up your camera to your computer for update transfers.) Be very careful that the camera does not turn off during the firmware update, or you could corrupt the chip in the camera, which would then require sending the camera back to the manufacturer to be fixed.

3.1.3. Input from Supplied Files

Supplied digital files are files that come into your workflow from other photographers or clients who need your specialized processing services, such as retouching, enhancements, further processing, or printing. Your input comes from a variety of customers with a variety of digital equipment, operating systems, and methods of image processing. These files can be and usually are in many different formats and conditions, and some may require advanced techniques in color correction, image manipulation, and proper use of a color space for color management (see Chapter 4).

As this chart indicates, once you transfer your files (RAW or JPEG) to your workstation or computer, the files can then be viewed in what I call the "Sales Room," where you will make master edits. These edits become your Selected Files and are then saved in your archival or backup system. Also, after the Master Edit, you can then print proofs or upload images to a website for viewing and ordering.




Practical Color Management. Eddie Tapp on Digital Photography
Practical Color Management: Eddie Tapp on Digital Photography
ISBN: 0596527683
EAN: 2147483647
Year: 2006
Pages: 61

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