Photoshop CS5 Enlightenment
Photoshop has become the go-to photo and image editing software used in advertising, photography, marketing, publishing, design and graphic industries around the world. This article discusses some basic setup features you can use with the latest iteration, Photoshop CS5, to your advantage in large-format applications.
By Jeff Burton, Digital Printing Analyst, SGIA
Photoshop coding began in 1987 on a Macintosh Plus. Thomas Knoll wrote the programming code to display gray scale images on a monochrome display. The program's basic functions included the ability to read and write various file formats, make selections and adjust levels, color balance, hue and saturation for color. In 1990, Photoshop 1.0 was first launched to the public as a Mac-only application.
Since then, Photoshop has become the go-to photo and image editing software used in advertising, photography, marketing, publishing, design and graphic industries around the world. This article discusses some basic setup features you can use with the latest iteration, Photoshop CS5, to your advantage in large-format applications.
Photoshop CS5 - code named "White Rabbit" as a symbol for the search for truth - was introduced in May 2010 and comes in two versions, "Basic" and "Extended."
The Basic version includes:
The Extended version includes:
- Complex selections made easy
- Content-Aware Fill
- HDR Pro and HDR Toning
- Puppet Warp
- Mixer Brush and Bristle Tips
- Easy 3-D extrusions with Adobe Repoussť
- Quick shadow creation and image-based lights
- Rich 3-D materials library
- Motion-based content editing
- Image analysis and measurement
The limitations in the program lie in the maximum dimension of the image and your available disk space: 1,000 inches by 1,000 inches or 300,000 square pixels is the largest image size you can use or create.
Photoshop CS5 is the first release that is fully 64-bit capable on both Windows (Win7 64-bit or Vista 64-bit) and Mac (Mac OS X Snow Leopard 10.6.x). Photoshop users can now take advantage of the full amount of memory installed in a system, which is particularly important in the case of desktop workstations. Workstations usually offer four to eight memory slots and make RAM expansion a cost-effective way of boosting Photoshop performance. If you have an operating system that runs natively in 32-bit, your system can't utilize more than four gigs of RAM, a serious limitation for working large files.
Memory is King
The amount of memory Photoshop requires depends on how you use the program. If memory is insufficient, Photoshop uses hard-drive space (scratch disk) to process information and is fastest when it can process all or most image information in memory, not using the scratch disk.
To check memory use in Photoshop, open the "Efficiency Indicator." Choose "Efficiency" from the pop-up menu on the status bar of your image to display the percentage of time spent actually doing an operation instead of reading or writing the scratch disk. If the value is less than 95-100 percent, Photoshop is using the scratch disk and therefore is operating more slowly. If the efficiency is less than 90 percent, you will see a big performance increase by changing your RAM allocation or by adding RAM.
In benchmark testing, jumps in performance will occur when moving from 4GB to 8GB or to 16GB of RAM; benchmarks conducted with 32GB did show slight performance increases over 16GB configurations, but only when working with very large files.
As a CS5 user, try to allocate a hard drive other than your boot drive to operate as a scratch disk (virtual memory) in case available memory is completely assigned. It is possible to get a "scratch disk is full" error even if the scratch disk drive has free space. This happens because Photoshop requires contiguous, un-fragmented free space on the scratch disk drive. Faster drives are better than slower ones (Solid State Drives, 7200rpm vs. 5400rpm) for this purpose. Do not use any network or removable drives as a scratch disk.
GPU Settings and Video Cards
The new CS5 prefers to use the onboard video card's Graphics Processing Unit (GPU). While you would hope that this would accelerate drawing and other redraw functions, I have found this not to be the case. For zooming, panning, toggling layers on or off, channel functions and more, disabling "OpenGL Drawing" might provide some relief from a sluggish or jerky screen refresh. When I disabled this automatic feature, I found relief from zooming jerkiness. This may be the opposite for your system.
While all Macs are video compatible, you can access an Adobe document to learn about specific video card compatibility for building a custom PC. Use the link: http://kb2.adobe.com/cps/831/cpsid_83117.html. If you are using a compatible card and are having video draw issues, try downloading newer drivers.
Setup for color management is the same as in previous versions of Photoshop CS or Creative Suite. To synchronize color management across the entire suite of products, use Adobe Bridge. If you want to do a custom color managed setup (not a preset), use one of the other programs (e.g., Photoshop, Illustrator, InDesign) that belong to the suite. You can use this saved color setting file to either send to another user or load onto other machines to use the same settings.
RGB Workflow Mojo
If you design solely for large format, I urge utilizing a red, green, blue (RGB) workflow. In today's work environment, RGB source art such as digital photos, illustrations and stock art are habitually "repurposed" and corrected for printing from various devices. You need a flexible workflow and a master image to tweak repeatedly to suit your output needs. The RGB color space does everything you need with its larger color gamut and dynamic range (compared to CMYK). In an RGB-preferred workflow, the master RGB image is quality adjusted and archived in RGB form. Duplicates may end up as a Web site graphic, a CMYK brochure, a large-format poster and more. Regardless of the output device used, you will be able to fine tune the color reproduction for each device. This is very different from the offset printing workflows that require a CMYK file for film or plate separation.
The key to utilizing an RGB workflow is to calibrate and profile (characterize) your monitor's software usage on a regular basis. Most software on the market today combines these two functions into one program for efficiency. Calibration adjusts a monitor into a precise set of conditions, creating a known environment. Characterization, synonymous with profiling, describes that environment to your color management system. Tools and software are available from Xrite, Datacolor, Pantone and ColorVision. Consistency in use is the key, since LCD monitors or older CRT monitors lose the ability to display correct color over time.
Choice of RGB Color Space
Color space refers to the color gamut or the range of colors available for capture, display or print. This illustration shows you the choices you have available in CS5.
The color space called sRGB was designated in 1996 through cooperation between Hewlett Packard and Microsoft and was meant to encompass the range of colors that most monitors, printers and the Internet were capable of reproducing then. It is still used when creating Web images or when exchanging information with other computers or users that do not (or cannot) recognize color space information embedded in image files. Inkjet photo printers are optimized for sRGB because the majority of people do not use an ICC workflow, and sRGB is the best choice for color matching between monitors and printers in an un-calibrated workflow.
Adobe RGB 1998
This working space was designed by Adobe Systems, Inc. to encompass most of the colors achievable on CMYK printers by using only RGB primary colors. It contains roughly 50 percent of the visible colors specified by CIE, improving upon the sRGB gamut chiefly in the cyan and greens.
What do you do with high-end digital cameras and scanners capable of outputting a larger color gamut than exists in sRGB? These wider gamut colors cannot be reproduced accurately when saved in the sRGB color space. If your digital camera or scanner allows you to work with a larger color space, like Adobe RGB, then take advantage of it. You can always convert an Adobe RGB image to a smaller gamut like sRGB. Converting an sRGB image to Adobe RGB will not produce a wider range of colors.
What about other RGB color spaces? ColorMatch RGB is available and was a default color space used in pre-press work, but is no longer manufactured for Radius CRT monitors. It remains in the list so that it can be used with older (legacy) ColorMatch tagged image files. Adobe also created the Apple RGB profile, based on the classic Apple 13-inch RGB monitor (introduced in 1987), and used it as the default RGB space in PhotoShop and Illustrator. Although the gamut of Apple RGB space is not much different than sRGB, it resides in many legacy files in the desktop publishing world. You do not want to use these color spaces in current day workflows for large- or wide-format output.
Screen Printer CS5 Upgrade Warning
Photoshop CS5 does away with the screening and transfer function within the Print dialog box that many screen makers use. The only way to get around the issue is to open your Psd file directly into Illustrator; you won't need to save dcs or eps files anymore. If you have created spot channel separations in Photoshop, then Illustrator will recognize all your spot channels as spot colors in the print menu. Turn off the CMYK colors and output your spot colors as you would normally, since Illustrator still retains the ability to adjust LPI/angle via the print dialog box.
Screen Print Film Adjustments - Levels or Curves?
To work around the missing transfer function, you can use "Levels" or "Curves" to modify the dynamic range of an image to compensate for dot gain. The easiest method is to use levels to adjust the output to match your process. If you don't know what your press capabilities are, first output to film a 100 Step wedge, make a screen and print it. You will see right away where your process falls off. Perhaps your process produces halftone dots only between 15 and 85 percent. From 85-100 percent is all the same value, and from zero to 15 percent there are no dots to be seen.
The following example is how you would adjust an image to accommodate 15-85 percent dot gain. Electronic files only have 255 discreet output steps available, so first decrease the contrast in the image and let dot gain work in a calculated manner. Change your black point from zero to 38.25 (15 percent of 255) and your white point from 100 to 216.75 (85 percent of 255). An easier, more customizable way is to use a "levels adjustment layer" with the same controls; the adjustments are not "burned into" the image. The major advantage is maintaining the original in case you need to make further refinements. While in the "layers" mode, try changing the blend mode from "Normal" to "Luminosity." This blend mode allows for lower contrast without the significant desaturation of the hue or chroma. In some types of images, the result of using the normal blend mode is too severe a reduction in overall color reproduction.
Using Curves will get you the same results as Levels does, it is just a different tool. Curves allows you to build in-between adjustments in addition to white and black endpoints. This helps since dot gain is not always linear in its appearance.
Unique Features Worth Using
One of the new, more applicable features I like is the "content-aware fill." This feature, like its predecessor, "content-aware scale," fills holes and removed objects with nearby imagery. Using this tool, you can recompose an image better than using a free-transform or basic-scaling technique. Content-aware scaling makes it easier to repurpose an image to a different proportion, without spending too much time on the project.
The new "refine" command used in conjunction with the selection tools is a great improvement. It is a step in the right direction for selecting fine details, fur, hair or anything that used to take a long time to mask around or isolate.
Blowing it Up
Enlarging or re-sampling small files that are sent to you by clients is the norm in large-format output. Re-sampling is changing the amount of image data as you change either the pixel dimensions or the resolution of an image. When you down sample (decrease pixels), information is deleted from the image. When you up sample (increase pixels), new pixels are added. You specify in the program an interpolation method to determine how pixels are added or deleted. For up-sampling continuous tone images, the choices are limited to:
- Bicubic: A slower but more precise method based on an examination of the values of surrounding pixels. Using more complex calculations, Bicubic produces smoother tonal gradations than Nearest Neighbor or Bilinear.
- Bicubic Smoother: A good method for enlarging images based on Bicubic interpolation but designed to produce smoother results.
Photoshop's built-in resizing methods work fine if you don't push beyond 200 to 300 percent, depending on the image and output resolution. There are other plug-in programs that do this task in a different way than Photoshop's interpolation scheme.
For example, OnOne Software has Genuine Fractals now called Perfect Resize 7, which makes use of a patented fractal-based scaling method. Or, Blow Up 2 from Alien Skin Software uses an innovative algorithm that temporarily converts pixels to a vector representation. While these are the two big ones in the industry, download your own free trial, use it in your workflow with client given images, compare the images to the same resampling that Photoshop has to offer and come to your own conclusions.
Saving Really Large Files
Graphic file formats vary in the way they denote image data (as pixels or vectors) and support diverse compression techniques or Photoshop features. To preserve all of the Photoshop features (layers, effects, masks, etc.), save a copy of your image in Photoshop format (PSD). Like most file formats, PSD supports files up to 2GB in size. For image files larger than 2GB, save them in the Large Document Format (PSB). TIFF format will save up to only 4GB in size.
Twenty-First Century Tool
Photoshop CS5 has many underlying strengths and I only discussed a few of its assets. Its benefit to you depends on what type of user you are and what products you will use this program for. Photoshop is still the industry standard application for editing and manipulating images and the most popular global program among design experts. Photoshop CS5 marks the 12th version of this global application package in the application's 20-year history.
Jeff Burton, SGIA's digital printing analyst, has served with the Association since 1998. He provides solutions to digital printing production, computer and workflow issues as well as digital equipment and vendor recommendations. Jeff received his B.S. in Photographic Science from the Rochester Institute of Technology and is a certified G7 Expert. firstname.lastname@example.org
This article appeared in the SGIA Journal, March/April 2011 Issue and is reprinted with permission. Copyright 2011 Specialty Graphic Imaging Association (www.sgia.org). All Rights Reserved.