Professional Photographer April 2009 : Page 52
THE GOODS: LABS Assembled by Andrew Darlow from Fuji and Kodak test targets; sepia image ©Andrew Darlow You can get better results from your lab with these five simple tips for better prints. BY ANDREW DARLOW Lab results SUPER-CHARGE YOUR LAB OUTPUT The technology behind continuous-tone printing in the digital photo lab is nothing short of amazing. Labs can quickly produce sharp, vibrant, long-lasting prints from wallet size to over 40x60 inches. Thanks to demand, digital lab printing is currently the most affordable high-end printing process. There are steps photographers can take on their end to ensure they get consistent, high- quality print results from their lab. I’m a big proponent of using custom profiles, but prob- lems arise when you send those profiles to a lab that uses multiple print devices, not to men- tion different makes and models. The resulting prints can exhibit color and density shifts. Assuming that your lab keeps its printers calibrated and color-balanced, these tips will help you get the best results. 1. Calibrate and profile your monitor. Calibration means measuring and adjusting the display’s controls for brightness, contrast and ambient viewing light, among others, until it reaches a known state. From there, you can build a “fingerprint” of that particular display, a.k.a. a custom profile. The custom profile should help your neutral images to appear neutral on-screen and your colors to look accurate. Consistency is important if you want to achieve the best results. I recommend using a hardware calibration device such as the X-Rite i1 Display 2, X-Rite ColorMunki or ColorVision Spyder3 to build your display profile. The viewing conditions 52 • www.ppmag.com (ambient natural light or artificial lighting type) and the characteristics of the display itself (laptop, glossy screen, LCD, etc.), have a significant impact on the appearance of the images displayed onscreen. Re-profiling is generally suggested every few months, and periodically viewing a target image can be very helpful. 2. Use a target image to test your monitor, as well as your lab’s output. After calibrating and profiling your monitor, use a target (test) image to determine whether the monitor is displaying colors accurately. Have the target image printed on different days, even on different paper surfaces, and compare the prints side-by-side to each other and to the image displayed on your monitor. This will also show if there are significant changes in the lab’s output from day to day. Try the test file available for download at www.andrewdarlow.com/ctest.zip. The file contains color and black-and-white images at a size of 280ppi on a 4x6 canvas. Because it’s saved in the sRGB working space in the Photoshop PSD file format, you can experi- ment with it without degrading the image quality—saving changes in JPEG format should be avoided when possible. The 21- step grayscale wedge is especially helpful for detecting color casts. The text in the image file will help you judge the sharpness of the lab’s output. Use a target file to test the accuracy of your monitor and consistency of the lab prints. Important: Instruct your lab to turn off all color correction, or you won’t be able to control the color and density of your prints. 3. Convert to sRGB before sending files to the lab. Many photographers shoot and process their files in the Adobe RGB (1998) or ProPhoto working space; most labs, however, expect incoming files to be converted to sRGB. To be safe, convert all lab-bound files to sRGB. In Photoshop: Edit > Convert to Profile > sRGB. In Adobe Lightroom, Apple Aperture, or another color-management aware application, choose sRGB when exporting. 4. Sharpen with care and use an appropriate file resolution. With so many means of sharpening images, rather than making specific suggestions, I recommend doing print tests with the kind of sharpening software you prefer. The resolution of your files in proportion to the output size is critical. Resolution too
Labs: Super-Charge Your Lab Output
Andrew Darlow
The technology behind continuous-tone printing in the digital photo lab is nothing short of amazing. Labs can quickly produce sharp, vibrant, long-lasting prints from wallet size to over 40x60 inches. Thanks to demand, digital lab printing is currently the most affordable high-end printing process.
There are steps photographers can take on their end to ensure they get consistent, highquality print results from their lab. I’m a big proponent of using custom profiles, but problems arise when you send those profiles to a lab that uses multiple print devices, not to mention different makes and models. The resulting prints can exhibit color and density shifts.
Assuming that your lab keeps its printers calibrated and color-balanced, these tips will help you get the best results.
1. Calibrate and profile your monitor.
Calibration means measuring and adjusting the display’s controls for brightness, contrast and ambient viewing light, among others, until it reaches a known state. From there, you can build a “fingerprint” of that particular display, a.k.a. a custom profile. The custom profile should help your neutral images to appear neutral on-screen and your colors to look accurate. Consistency is important if you want to achieve the best results.
I recommend using a hardware calibration device such as the X-Rite i1 Display 2, X-Rite ColorMunki or ColorVision Spyder3 to build your display profile. The viewing conditions (ambient natural light or artificial lighting type) and the characteristics of the display itself (laptop, glossy screen, LCD, etc.), have a significant impact on the appearance of the images displayed onscreen. Re-profiling is generally suggested every few months, and periodically viewing a target image can be very helpful.
2. Use a target image to test your monitor, as well as your lab’s output. After calibrating and profiling your monitor, use a target (test) image to determine whether the monitor is displaying colors accurately. Have the target image printed on different days, even on different paper surfaces, and compare the prints side-by-side to each other and to the image displayed on your monitor. This will also show if there are significant changes in the lab’s output from day to day.
Try the test file available for download at www.andrewdarlow.com/ctest.zip. The file contains color and black-and-white images at a size of 280ppi on a 4x6 canvas. Because it’s saved in the sRGB working space in the Photoshop PSD file format, you can experiment with it without degrading the image quality—saving changes in JPEG format should be avoided when possible. The 21- step grayscale wedge is especially helpful for detecting color casts. The text in the image file will help you judge the sharpness of the lab’s output.
Important: Instruct your lab to turn off all color correction, or you won’t be able to control the color and density of your prints.
3. Convert to sRGB before sending files to the lab. Many photographers shoot and process their files in the Adobe RGB (1998) or ProPhoto working space; most labs, however, expect incoming files to be converted to sRGB. To be safe, convert all lab-bound files to sRGB. In Photoshop: Edit Convert to Profile > sRGB. In Adobe Lightroom, Apple Aperture, or another color-management aware application, choose sRGB when exporting.
4. Sharpen with care and use an appropriate file resolution. With so many means of sharpening images, rather than making specific suggestions, I recommend doing print tests with the kind of sharpening software you prefer.
The resolution of your files in proportion to the output size is critical. Resolution too Low will result in softness and lack of detail.
Where it becomes too low depends upon the lab’s printer and internal RIP, but I recommend saving the file at least at 200ppi at the desired output size. Test a few resolution and file size combinations. The bottom line is that you don’t want to spend extra time sending larger files than you need to.
For more on this plus a size-to-resolution chart, go to http://tinyurl.com/reschart.
5. Find the best, most economical JPG compression. JPG compression quality varies greatly with the amount of compression you select, and to some extent, the amount of detail in the image itself. For high-quality prints, using Photoshop’s scale of 1 to 12, I recommend at least 9. Testing a few JPG compression levels is worth the cost of a few prints, because then you’ll know at what point image degradation occurs.
Publication List
