Photographic Art Reproduction Best Practices and Techniques Nicole Leclair May 2014
Abstract The goal of this publication is to provide the reader with a thorough explanation of the devices and techniques necessary to create an accurate photographic reproduction from initial capture to final print. Ensuring color accuracy is essential in creating quality photographic reproductions of artworks. Nitin Sampat’s Color Management class at the Rochester Institute of Technology has explored the process of creating color-accurate art reproductions. Choices and methods of choosing measurement devices, photographic equipment, software, displays, etc. will be explained. Techniques for measuring reference colors, characterizing devices, operating essential software, printing, troubleshooting, and object handling will also be explored. Less technical concerns for the successful operation of a reproduction business will also be discussed.
Process Overview Capture
Process
Create Camera Profile
Create Monitor Profile
Create Media Profile
Photograph Artwork and References
Assign Monitor Profile in Computer Operating System
Assign Media Profile to Corresponding Images
Assign Camera Profile to Corresponding Images
Neutral Balance, Crop, and Resize Images
Print Desired Images
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Art Reproduction Best Practices and Techniques Nicole Leclair, May 2014
Introduction
While color accuracy may be considered the most crucial in creating photographic reproductions of artworks, the process of ensuring color accuracy can be beneficial to any photographic workflow. This tutorial explains the processes involved in color management between all devices and media needed for the reproduction of artworks. The proper equipment, applications, and techniques are discussed.
The Problem
The various media, devices, and lighting situations that contribute to the creation of art reproductions can cause a significant discrepancy between the way color appears on the original artwork and the final reproduction print. Reproductions are expected to be as true to the original as possible. Photographic reproductions are especially tricky, as an object in oil, watercolor, acrylic, etc. must be translated to a digital file, and then to an inkjet print. There is a significant difference in the gamuts of paint media and print media. A thorough understanding of the media, devices, and lighting involved, as well as the best ways to utilize these components, will aid the photographer in creating the most accurate reproduction possible.
Equipment
The first major decisions one must make in order to begin an art reproduction business involve which equipment to purchase or rent. While a full set of equipment represents a large investment, it is recommended that the artist purchase these items rather than rent them for every job. Device consistency and a total understanding of the characteristics of devices used are necessary for the most effective and color-accurate workflow. Capture Camera In order to decide which camera to purchase, on must determine the size of the artwork to be photographed and reproduced. The following equation can be used to determine what camera resolution is needed to reproduce a work of art: Camera Resolution = Output Resolution x Magnification x 2 In which Output Resolution describes the resolution capabilities of your printer, magnification describes how many times bigger your final print is than the original, and the factor of two allows for error or deviation from anticipated size. In art reproduction, typically the magnification is one, as a 1:1 reproduction is most commonly requested. Resolution is expressed in pixels per inch. Suppose a 2-foot by 3-foot painting will be reproduced at its original size. The minimum number of pixels (the resolution) needed to reproduce this piece is: (24in. x 300 dpi) x (36in. x 300 dpi) = 72,760,000 pixels According to these calculations, the only device capable of resolving this image at the desired size is a digital scanning camera such as the Better Light (and this is without the suggested doubling of this value to ensure the image will be resolved). However, the high cost of a scanning camera may encourage the photographer to seek out alternatives. The equation used does not have to be an absolute rule. The photographer can experiment with what they consider to be common sizes of artworks they will need to reproduce, photograph them with a higher-end DSLR, and test the camera’s capabilities in resolving the image at the desired size. It may be less expensive to use a DSLR for smaller artworks and rent a scanning camera when necessary. The cost of purchasing a scanning back camera can range from $5,000 - $20,000. A suitable DSLR will cost roughly $3000. 3
Lens A suitable lens will cost about $2000. A 50mm macro lens capable of the tilts and shifts needed for perspective control is recommended. These features prevent any distortion of the art object and give ultimate focus control. The art object must be perfectly in focus for an ideal reproduction. This is a challenge due to the three-dimensional nature of many paintings. The focus must cover a range of a few millimeters to a few inches depending on how raised the highest surface of the painting is. Taking care to manually focus the lens is recommended to have the desired result. Image Processing Monitor NEC brand displays are some of the highest-quality monitors available. The NEC series of ColorAccurate and Color-Critical displays are ideal for photographers. The price, dependent on size, ranges from $1000 - $2600. Less expensive displays can be used but should be calibrated regularly, and the user must understand its limitations. Software Image-processing software such as Adobe PhotoShop will be needed to crop and neutral balance images, apply camera and printer profiles, and to print the reproductions. The latest version will cost $360 per year with a Creative Cloud subscription. Software to create camera, monitor, and printer profiles will also be needed. X-rite’s ProfileMaker software (plus hardware dongle) creates profiles for a number of devices using test target values, images, and lighting information. However, this software has been discontinued. A more recent profiling software is called Eye-One Publish Pro, also by X-rite. Profiling software will cost about $2000. A RIP, or Raster Image Processor, is also recommended for a controlled workflow. RIP software gives the user added control over color, speeds up the processing of print jobs, and can help minimize wasted paper by “nesting” multiple images onto one area of paper. RIP software will cost about $5000. Printing To allow for 1:1 reproductions of large pieces, a wide-format, 44-inch printer is recommended. The Epson Stylus Pro 9880 uses eight inks and can handle a number of media types. A printer of this size and capability will cost about $5000. As reproductions are expected to last quite some time, the selected printer should use archival pigment inks. Other Equipment A set of reference colors will be used to compare a known set of color values to the photographed or printed version. Greytag Macbeth produces reference color patches in the form of ColorCheckers. A standard ColorChecker card costs $70. A spectrophotometer is the most accurate device to measure color. It can be used to measure color patches, monitors, and light sources. X-rite’s i1Photo Pro 2 performs all necessary functions for color management. This spectrophotometer costs $1500. Using the same spectrophotometer for all color measurement needs is recommended to maintain consistency. The industry standard viewing illuminant is a D50 light source. D50 lights can be installed in the room the object and reproduction are being viewed in, or a D50 viewing booth can be purchased for $1000 $2000. Keep in mind that prints are being produced to be displayed in a specific environment, and the viewing environment while printing should reflect the end location if possible. D50 is a reasonable viewing illuminant if the final lighting situation is unknown. The lighting situation should also remain consistent Two types of ColorCheckers, the Classic and SG, being between the monitor and the print. photographed in a studio 4
Calibrate & Characterize Using an ICC Workflow
To calibrate a device, it is brought to a known state in known conditions. This is a fast process and can be done frequently (daily) to ensure consistency in the camera, monitor, and printer. Characterizing a device is a slower process and can be done less often (monthly). Characterizing is the process of determining the performance of a calibrated device (in this case, determining a device’s color capabilities). Camera Calibrate Reset and reprogram all camera settings and preferences regularly. Characterize Measure spectral data from each patch on the test target that will be photographed, such as a Macbeth ColorChecker, using a spectrophotometer. Ideally, each color patch on the test target will be measured three times, and then the values are averaged to create a profile. The software will create a .txt file containing the spectral data. Software such as MeasureTool can average the values from the three .txt files that ProfileMaker creates. The resulting .txt file will be loaded into ProfileMaker to generate the camera profile. Next, photograph this test target using the calibrated camera that will be used to photograph the artwork. Measure the spectral power distribution of the light source the ColorChecker and artwork will be photographed under using the spectrophotometer with the diffuser attached. Load the measured spectral data, lighting information, and the sample image into profiling software. The software will create a custom profile for that particular camera and lighting combination. Monitor Calibrate Reset and reprogram all display settings and preferences regularly. Characterize A device such as X-rite’s ColorMunki or i1Photo Pro 2 can be mounted to a monitor in order to characterize the device. The software will display a series of colors to the ColorMunki, which will measure the monitor’s capabilities. A simple but fairly reliable monitor calibration/characterization is to assign an sRGB profile. Printer Calibrate Printers can be calibrated based on density measurements of printed color patches. Print and measure daily. The printer will make adjustments based on these values. Characterize Print (without color management) the appropriate test target for the device to be used to measure spectral data. Adobe Color Printer Utility allows the user to print without color management. Measure the printed test target using a spectrophotometer in conjunction with profiling software (ProfileMaker) to generate a printer profile based on reference data, measured data, and the viewing illuminant (the lighting conditions that the final print will be viewed in). Ideally, each color patch on the test target will be measured three times, and then the values are averaged to create a profile. To automate this process, a useful tool is the i1 iO. The i1 spectrophotometer can be placed in this device, which will automatically move it across the test target, measuring each patch. The software will create a .txt file containing the spectral data. Software such as MeasureTool can average the values from the three .txt files that ProfileMaker creates. The resulting .txt file will be loaded into ProfileMaker The EyeOne spectrophotometer mounted to the i1 to generate the printer profile. iO to measure a test target for printer profiling
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Reference data and measured test target data are loaded into ProfileMaker in order to create an ICC profile for one printer/media combination
.txt files with measured spectral data may be loaded into MeasureTool in order to average the values to create the most accurate ICC profile
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Assign ICC Profiles Camera Copy generated profiles onto the computer’s color management folder. On a Mac, this folder is called “Color Sync”. In Windows, there is a Color Management section within the Control Panel. One may also right click on a profile and select “Install Profile”. Once a set of photographs has been captured and loaded onto the computer, the appropriate camera profile can be applied in PhotoShop using the Assign Profile command. Monitor Monitor profiles are installed into the computer’s operating system. Printer The printer profile will also be applied in PhotoShop or a RIP. Once the profile has been installed, select “PhotoShop Manages Colors” in the print module and select the custom printer profile for the printer/media combination from the drop-down menu.
Select the printer, profile, rendering intent, media type and size, etc. in the print module
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Alternative Color Pony Workflow An alternative to using the ICC camera profiling process, Color Pony software creates a color-corrected TIFF file that can then be brought into image processing software, cropped, and printed with an ICC printer profile. Instead of measuring color patches from a reference card, Color Pony encourages measuring reference colors (between 20 and 30, using the spectrophotometer) directly from the artwork for further color accuracy. When photographing the artwork, the photographer will also photograph a white reference card that fills the frame (the card must be the same size or larger than the artwork). This allows for the software to account for uneven light distribution. Because of this adjustment ability, the photographer may use one raking light on the artwork if desired to show more texture. The white reference must be measured with the spectrophotometer at about six points. After making the photographs, Color Pony allows the user to select from a list of camera and lighting situations, or enter their own custom setting. Only certain cameras are supported, so the photographer should ensure that they have the appropriate equipment before investing in this software. The user will upload the white reference image, the image of the artwork, and the spectral data for the reference colors and white reference. A group of images made with the same camera in the same lighting situation and with the same reference colors and white reference can be batch processed. Once the users clicks “Yoke It!,” the software will process the image and create a new TIFF file with the extension “_yoked” in the same folder as the source image.
Art work and white reference photographs, as well as reference colors and white reference spectral data are loaded into Color Pony to be “yoked”
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A white reference card lit by two North Lights in a studio. Color Pony will adjustfor any variations in lighting across the reference card
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Troubleshooting A common issue that can result in poor color reproduction is an error in the creation of an ICC profile. There are a number of ways to determine where the root of the issue is. Plotting the profile in software such as Gamut Viewer can show the user any irregularities in the profile upon visual inspection. Determining whether the issue is in the camera or printer profile is simple: if the color appears incorrect on screen with the camera profile applied, the issue is in the camera profile; if the color appears correct on the screen, but incorrect in soft proofing or after printing, the issue is in the printer profile. The appropriate profile should be re-created to resolve this issue. An image may also simply be out of gamut for the printer being used. Adding more inks or changing the paper type may resolve this issue. Printers are extremely sensitive and can vary from day to day. Regular calibration and characterization can help prevent variations, but they are still a possibility. It may be worth recalibrating and re-printing to try to resolve a print quality issue.
A custom printer profile for printing on HP canvas is plotted in Gamut Viewer
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It is essential to specify the media type, weight, and size in the printer driver settings
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Photographing the Artwork The photographer has a few things to keep in mind when photographing for reproduction. First, the image plane should be precisely parallel to the object plane. The focus also needs to be exact. While a digital scanning back can produce extremely sharp and detailed images, focusing can be a challenge. A loupe can assist the photographer in focusing on the ground glass of a 4x5 view camera. ViewFinder, the software for using the Better Light scanning back, also has a digital focusing option that, with some practice, can be helpful in difficult focusing situations. The photographer should closely examine the resulting image and be certain that the object is in focus before removing the object from the studio. If the photographer plans to use the Color Pony method, the white reference card needs to be photographed first. The photographer will find the correct exposure using the white reference, and then leave the framing, camera position, and exposure settings the same to photograph the object. The object should be on the same plane (in the same position) as the white reference was. This ensures that the software will compensate for uneven lighting properly. The most commonly used lighting setup involves two lights at 45 degrees from either side of the object. Moving the lights closer to the object will decrease the required exposure time, but care should be taken not to bring lights (especially those that emit noticeable heat) too close to the object. Raking light (one light placed nearly parallel to the object plane) may be desired to highlight the three-dimensional nature of the artwork. The Color Pony method is recommended in this situation in order to compensate for the dramatically uneven lighting.
A studio setup with two North Lights, a 4x5 view camera, and white reference
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Object Handling If the customer leaves the original artwork in the reproducer’s care in order to be photographed, the art object should be handled with the utmost care. As outlined above, the photographer should discuss with the customer any concerns for the handling of their artwork. White cotton gloves should always be worn when handling the object. When the object is not being photographed or measured, it should be in a safe place that only authorized persons have access to. Valuable works of art should be photographed vertically, in which the object is wallmounted with the camera parallel. Nothing should ever be above the piece to ensure that nothing ever falls onto the surface. The object should be in direct light for photographing for as short a time as possible. Food and drinks should not be eaten or kept near the object. If the object is not framed or mounted on a stiff surface, care should be taken to keep it flat at all times. When mounting the object on a studio wall to be photographed, the handler should ensure that the object is secure (preferably by all corners for an unmounted object). The photographer should keep a clean and clear space where the handler will not trip on or bump into anything while moving the artwork.
Spectrophotometer measurements are made carefully, on a clean surface, with minimal contact with the artwork, by a handler wearing white cotton gloves
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The artwork is being kept as flat as possible and handled by edges only with white cotton gloves
Location The most ideal location to photograph artwork is a controlled studio environment. In this situation, the photographer has full control of the lighting, equipment available, power source, etc. However, it is very common that the photographer needs to photograph the artwork as it hangs in a museum or gallery. This environment is less predictable and less easily controlled. If possible, the photographer should visit, analyze, and measure the environment before the date of the photo shoot. Portable light kits may be preferable to the existing light on location. A stable power source will be needed to operate a digital scanning back to prevent unrecorded lines or pixels.
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Digital Asset Management It is essential that all digital files be organized and easy to locate quickly. For example, one may keep dedicated hard drives for personal work and professional work. Within these drives, projects could be divided by date, location, or client. Unprocessed image files should be separated from archival copies and the final printed TIFFs. Ultimately, the photographer must determine what organization methods are the most logical for their personal navigation. This also applies to the file naming convention. This format for naming files should be an early decision to ensure that all image files follow the same, searchable naming convention. README files explaining naming conventions and what was done to the image file can accompany the digital files to ensure that the process may be recreated in the future if needed.
A file naming convention that explains the date, photographer(s), camera, and subject
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Printing on Canvas Choice of Canvas For archival-quality reproductions, the highest quality canvas should be used. The best canvas will be very flexible. A flexible canvas indicates the quality of the gesso applied by the manufacturer. This flexibility ensures that with stretching, bending, and swelling, the image will not crack or flake from the canvas surface. After the gesso layer is applied, the manufacturer applies an inkjet coating. The gesso and inkjet coating need to be compatible both with each other and with the inks the printer selects. It is safest to use brand-name canvas and inks to ensure that all materials involved will create a successful archival print. A variety of online resources are available both from the canvas/paper companies as well as third-party consultants such as Henry Wilhelm that explain the results of various ink and media combinations. Matte canvas is recommended, as with “metallic” or glossy canvas, the ink sits on top of the surface. A variety of textures are available for matte canvases, from smooth to very textured. Recommended canvas companies include Canson, Hahnemuhle, and Fredrix Canvas. Treating the Canvas After printing the reproduction, the printer will wait roughly 24 hours before applying a protective clear coating to protect the reproduction from air pollutants, water damage, light fading, and abrasion. Clear coatings can be either water-based or solvent-based. To use a water-based coating, the canvas must be water-proof. Five coatings with one hour between coatings should be applied for best archival quality. For clear coatings, Clearstar is recommended.
Understanding Customer Needs The following are some issues that should be addressed when accepting a reproduction job from a client. These questions will not only ensure that the job is performed properfly, but also assure the customer that their artwork and investment is safe in the photographer’s hands. Original Artwork What size and on what media is the artwork? Is it framed behind glass? Was it made on or mounted to a sturdy, inflexible support? Is it sturdy enough to be photographed vertically? What are the handling concerns for this object? Is the object sensitive to heat, humidity, abrasion, etc.? Can measuring instruments come into contact with the surface of the object? Final Materials What size and on what media will the final reproduction be? Does the artist want to add embellishments or texture after the reproduction has been printed? How archival does the client want the reproduction to be? (This will affect the materials used and price) In what environment will the reproduction be displayed? (Type of lighting, air pollutants present, etc.) Other Concerns In what timeframe does the customer need this reproduction finished? What is the customer’s budget for this reproduction? Is the customer comfortable signing a contract that explains the photographer’s procedures and explains liability? 16
Glossary Calibrate To bring a device to a known state in known conditions. Calibrating a device helps to stabilize its performance. Characterize To determine the capabilities of a device, often using a spectrophotometer and profiling software. D50 The industry standard color temperature of a light source, represents 5000 Kelvin Digital Scanning Camera Inserted into the back of a view camera in the place of a film holder to create extremely high-resolution digital photographs. ICC Profile Created after device characterization, an ICC profile contains a formula to tell a device how to interpret the color values provided in the image file. Gamut The range of colors that a device is capable of capturing, displaying, or printing. Resolution In this case, the spatial resolution of a device explains the number of pixels in the x and y dimensions. A higher spatial resolution is needed to resolve a very detailed image such as a painting with significant texture or larger images. Spectrophotometer The most accurate device for measuring color. Provides spectral data to be used in characterizing and profiling devices. View Camera An older style of camera comprised of a front standard holding a lens, bellows, and rear standard holding ground glass (the focusing plane) and a film holder.
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