DIGITAL IMAGES PLAY an important role in collections management and reduce the need for an object to be moved or handled unnecessarily. Although objects constitute the primary collection holdings of any institution, a collection of related digital images is a valuable resource for many constituents in and outside the institution. For registrars, object photographs can serve as visual documentation of the collection, provide detailed views of an object’s condition, record the scene of an incident and the resulting damage, or supply an appraiser with the information needed to assess an object’s value. In addition, other departments in the museum use object photographs in a variety of ways. Conservation uses images for study and treatment projects. Marketing and the public relations departments use images for social-media campaigns, exhibition banners, brochures, posters, and newsletters. Exhibition designers incorporate images into their designs. Museum educators include object photographs in lesson plans and public programming. Researchers employ images in publications and online research portals.
The quality of digital cameras and monitors available on the market is rapidly evolving and currently there are few agreed-on industry standards for imaging technology. In an effort to standardize imaging practices in museums and research institutions, a consortium of federal agencies developed Federal Agencies Digital Guidelines Initiative (FADGI) in 2007.1 FADGI is a collaborative effort to articulate common sustainable practices and guidelines for digitized and born-digital historical, archival, and cultural content. These agencies maintain a website2 that contains a vast range of useful imaging information. Professional photographers working in the museum context should employ FADGI standards in their work.
This chapter is intended as an introduction to digital imaging terms and best practices. Because reg istrars are often asked to photograph objects or work directly with photographers, it is helpful to know the basics in museum photographic practices. It would be easy to dedicate an entire book to the intricacies of working with and archiving digital images in the museum context. For those readers who would like to gain more familiarity with imaging equipment or software than what we can offer here there is a world of excellent tutorials and video resources available on the internet. The best place to start is the FADGI site and camera vendor-based sites that are geared toward the professional market. Detailed information about a wide range of topics can be accessed through Adobe software tutorials, Phase One, Capture One, and Linda.com.
Before turning off the lights to start shooting, it is important to understand how photography is used in the institution and how it relates to the mission and long-range goals.
It is important to continually assess institutional needs for imaging.
A sound strategic plan should start with an examination of the types and scope of photography the museum already has. Most museums use a mix of several different types of images because they incorporate new photographic technologies while maintaining the previous methods as long as is practical to do so. Many institutions are digitizing some, if not all, of their analog image holdings. Analog images include old transparences (i.e., color slides), prints, black-and-white films, etc. Although there are needs that are well-served by such images, it is important to weigh the costs of digitizing and digital storage of these files against their actual use. Making all these visual resources available via collection management software can enrich the quality of visual information related to an object. Scanned analog images can provide invaluable information about the past condition of an object, installation needs, and exhibition records. But the scanning, file cleanup, and related digital data storage and maintenance of those assets comes at a cost. Many collections of old transparencies or film have not been stored properly and suffer from fading, dirt, or discoloration. An institution should involve all the related stakeholders when assessing the practicality and need for scanning analog images. There are times when an institution may need to forgo a costly scanning project to allocate resources to generating new, higher quality digital images of objects.
Most institutions understand that they need to be more open and facilitate greater access to their collections, and this is true of image archives as well. The current trend is for museums to open their archives to the public, but not every institution has the financial, technical, or staff resources to support full public access. Museums need to assess and formulate a clear policy governing who may use their images and how. Object photography is frequently used by the museum’s registrar to document the collection visually and enhance object records. Although a registrar will need access to all of the object images in a database, each institution should carefully assess which of those images can be made available for public use. Object photographs represent the public face or brand of the institution, and once a digital image is made public, the institution will not be able to control how it is circulated. The institution should codify who will have access to images documenting condition issues, conservation work, or other potentially sensitive visual data related to an object. All staff should be familiar with museum policy about how and when those images can be used.
Any decisions about in-house, public use, or sharing of an image database must start with examining the institution’s long-range goals and strategic plan. Does the institution have a long-term plan for the safe storage, maintenance, and ongoing upgrades of a digital archive? Are there basic metadata and image quality or file standards in place to make searching possible? Does the institution have a digital asset management system (DAMS) or collections management system (CMS) to organize and access image assets (see CHAPTER 4D, “Digital Asset Management Systems”)? These questions are important if a museum intends to make any part an image database available online.
Like all programs and operations, photography requires space. A good photography space requires three things for success: enough room to house the photographic equipment, space to accommodate the object(s) to be photographed, and the capability of being completely dark. Ideally, photography should be done in a rectangular, windowless room that can be made completely dark. This type of room allows for multiple setups. However, if such a room is not available, compromises are necessary. Photography can be done nearly anywhere, although each space will have its own advantages and disadvantages. The best way to think about the size and amount of space needed for photography is to consider the sizes and types of objects in the collection to be photographed. A collection consisting of mostly works on paper will have different photographic space needs than a collection of large-scale paintings and sculpture. If options are limited and a dedicated space is not available, be creative and consider all the spaces in the museum. Galleries are often suitable for photography if they can accommodate a large number and variety of objects and photographic equipment. An auditorium stage is typically roomy enough to accommodate most types of photography as well. Another possible space for photography is the storage area, although the types and arrangement of furniture may limit its usefulness.
The final and probably most important thing to consider is the budget. The amount of money available for object photography will dictate what can be accomplished. Whatever amount the institution is able to invest in photography, it should be used to fulfill the goals of the institution.
Digital photography, as we know it today, was introduced by Nikon in 1986 but was not commonly available till the mid-1990s. It took another ten years for consumer digital cameras to supplant film. Although all digital cameras consist of three primary parts, they do vary in quality. This section is designed to help anyone who may need to purchase equipment or is working with a freelance photographer. When hiring a photographer it is good practice to inquire about past photography experience and the type of equipment they intend to use.
The camera sensor plays a critical role in image size, resolution, color accuracy, and dynamic range (the accurate representation of light values from white to black). The sensor determines the overall quality of image and how much it can be enlarged. The quality of the sensor is determined by the size of its pixel array.
There are two types of sensors—charged couple device (CCD) and complementary metal-oxide semi-conductor (CMOS). CCD has been around longer and for many years was considered to be superior to CMOS. CCD sensors tended to produce less noise (unwanted color artifacts that show up as specks of light or color in the dark area of an image) and have better light sensitivity, but they have traditionally been more expensive to produce and require more power to operate. This resulted in CCD sensors being used in the more expensive professional cameras, whereas CMOS sensors are used in smaller point-and-shoot cameras that do not need to provide as much power. This trend is starting to change in the very high end of the professional camera market. When choosing a camera, you should opt for a full-frame sensor when the budget permits. There are several advantages to using a full-frame sensor including a wider angle of view and more control over depth of field.
An image processor is the camera’s built-in computer and can impact image quality in several ways. First, it determines how quickly sensor data is converted into an image. A camera with a high-quality sensor and slow processor will take a long time to produce a visible image. Camera sensors are programmed to make calculated adjustments for a wide range of lighting and color scenarios. All light is made up of color and colors change, based on the time of day, shade or sun, light source, and light intensity. Shooting in light that has a color cast or in a room with colored walls will negatively impact the color accuracy of the image. A good image processor can help generate an accurate white balance and provide other image adjustments that improve image appearance and shooting speed.
A high-quality lens is a critical component in maximizing sensor and image processor function. Cameras with high-quality digital components require a higher grade of optics to function at their optimum level. When purchasing equipment, one should buy the best possible lenses that the budget allows. There are several internet sites that post the results of lens comparison testing that can help with research before buying. A good lens will be sharp all the way through an image, have minimal chromatic aberration or color fringes along the edges in areas of high contrast, and have little to no distortion of the image.
A good initial investment is at least two fixed focal length lenses. If you have a full-frame camera, one lens should be a general 50-mm lens and the other a macro lens, used for close-up, detail images. If your camera does not have a full-frame sensor, you should consult with a reputable camera dealer for suggestions on which lenses would be the equivalent in focal length. There are other factors that may impact the price of a lens. For example, a lens that offers image stabilization will cost more. Another factor in price is the lens speed. A fast lens has a large maximum aperture opening, which is a great advantage if the goal is to properly focus and take photos in low-light situations.
A digital image can be saved in a variety of file formats. Each format has advantages and disadvantages. When working with different file formats, keep in mind the capability of the camera, how the images will be used (viewed), and how much storage space is available for the file. Regardless of file type the amount of loss in a digital file is determined by the algorithm used to compress the image, both in the camera and once the image has gone through postprocessing software. Some camera algorithms discard no information, others discard some information, still others look for recurring patterns and replace each occurrence with a short abbreviation to reduce the image size.3 The amount of loss determines the level of degradation within the digital image. This, in turn, will impact how the image can be used and how much storage space it will require. The most common file formats currently employed in digital imaging follow.
Professional photographs start with a well-exposed camera RAW file. RAW files contain all the data that the sensor is able to register, but they do require an advanced knowledge of image-processing software, such as Adobe Bridge or Capture One. RAW offers the ability to access and display a wide range of data. When done correctly, any changes made to a RAW file during postprocessing are completely reversible. This unique ability to access image information and control over final appearance makes camera RAW a superior choice over any automated changes that can be made by an in-camera processor. However, RAW format is not appropriate for every situation or user. As of 2019, the RAW file format was not standardized across camera manufacturers. RAW files are still camera proprietary files that cannot be opened or viewed by other programs. If left in their original, unprocessed state, RAW files can become obsolete over time. The files are large in size and cannot be viewed without the appropriate software. For those who do not know how to work with RAW files or do not have the needed software, it is recommended to convert RAW files to 16-bit, Adobe RBG 1998, TIFF files. The color correct TIFF file should serve as the master file; a needed JPEG may be derived directly from the master TIFF file.
If a camera does not have an option to shoot in RAW mode or if you are not familiar with nondestructive color editing in Photoshop, the next best option is to select the high-resolution TIFF mode in the camera menu. TIFF files use a lossless compression that does not throw away file data, as is the case with JPEG files. You will not have access to the range of image information that a RAW file has, but a TIFF file will retain full image resolution and can be viewed by other programs. This makes TIFF the ideal choice for any master files that go into an image archive.
The most common file format is JPEG. This format uses different levels of image compression, allowing for reduced file size and easy sharing via the internet. Because JPEG is a “lossy” compression, each time an image is saved as a JPEG, image detail, color accuracy, dynamic range, and resolution are reduced. Repeated resaving of a JPEG file results in a degraded image that cannot be repaired. As a result, shooting in the JPEG format in the camera should be avoided when possible.
For a detailed reference of the current technical standards for digitizing different cultural objects, refer to the FADGI’s Technical Guidelines for Digitizing Cultural Heritage Materials.8
Color, intensity, and light direction are the three most critical components to any photograph. Natural and artificial light sources emit a variety of color temperatures, which can affect the color accuracy of the image. One measure of light is color temperature, which is expressed using the Kelvin scale (K). Visible light temperatures cover a wide range, from 1000 K (the warm glow of a candle or late evening sunset) to the blue 6500 K cast of monitors (and some fluorescent tubes). Tungsten lighting, used in many gallery settings, emits a yellow light. A shady room with ambient window light will usually have a blue cast, as do most on-camera flash units. Daylight of around 5500 K is neutral in color and is the standard for most photographic lighting. Mixed temperature lighting or colored walls will cause changes in how object color is perceived. In the days of film photography, mixed lighting situations were difficult to properly correct for, but the advent of white balance settings and advanced postprocessing software have greatly improved our ability to accurately correct color.
There are two ways to fix unwanted color casts in an image while shooting and in postproduction. To maintain color accuracy, it is critical that the photographer maintain control over the color and quality of lighting used when photographing objects. For a registrar, who may not have a lot of photography experience, it is best to start with a set of daylight-balanced continuous LED lights. These can be mounted to light stands and are also useful when examining objects. Unlike professional flash or strobe lights, which produce a harsh light for a short duration, LED lights make it easy for anyone to see the direction and intensity of the light. If the light is too harsh, or the angle of the light is creating too many shadows, adjustments can easily be made (e.g., by moving the camera further from the object). The quality and cost of LED lights varies so it is important to work with a reputable photographic equipment dealer to determine which make and model will provide the most accurate light output for object photography.
Even when an image is made using daylight balanced lights, some white balance adjustment will still be necessary. Setting a custom white balance in your camera or adjusting the color via software while shooting tethered to a laptop is highly advised. Each camera model has specific instructions, but the fundamental steps are similar. Use a clean, smooth, white seamless piece of board or paper that is big enough to fill the frame of the camera. Make sure the paper or board you are using is not yellowed with age. Set up the light source and place the white background where your objects will be positioned, keeping it completely parallel to the camera. Focus the lens and follow the camera’s custom white balance instructions to create a custom white balance profile. If the lighting or camera position are not changed this setting should render a neutral lighting color. Because the color temperature of lights can change as bulbs age, it is a good habit to do a new white balance profile each time the camera is set up.
Current best practices for museum photography dictate that a color checker or scale should be included in the image. A color checker or color scale is a precisely printed, scientific color or grayscale grid used to calibrate color balance. Each color patch has a value that matches an exact red, blue, and green (RBG) equivalent. Color rendition charts were originally employed in the printing industry to confirm that specific colors were reproduced accurately. Color charts for photography vary in size and number of patches they display, but they should always include a black, an 18 percent gray, and a white swatch.
Placing a color checker in the frame provides important reference data for anyone doing postprocessing on the file or using the file for printed reproductions. By measuring the color on the white, black, and gray swatches, an experienced photographer can deduce information about image color and contrast range. Although this chapter is too brief to provide specific instructions, there is extensive online information on color balancing images and using color checkers and scales in combination with Adobe Bridge or Capture One software.
In digital photography, color management begins with the color model in use—RGB, the color model used for digital capture and display, or CMYK (cyan, magenta, yellow, and black), the color model used for printing. Digital images taken in the RGB mode are device dependent “in that each different device detects and reproduces the amount of Red, Green, and Blue differently.”9 These differences are noticeable when transferring images from one device to another. To correct this problem, the International Color Consortium (ICC) was formed in 1993 to establish a universal color management system that would work across various platforms.10 To accomplish this, the ICC created color profiles. A color profile describes the color spaces of a particular device.11 For example, when images are transferred from camera to computer, the computer reads and converts the information into defined colors based on its color space. If the camera’s color space is different from the computer’s, the colors in the resulting images will be different; color profiles are used to correct this problem. The color profile describes the color space used by the camera to the computer, which then converts the information it receives into the correct colors. The result is a new image that looks as similar to the original image as possible.12
RGB, sRGB (standard red, green, and blue) and CMYK are currently the most common color models used in digital imaging. RGB is an additive color model used by any device that has a screen, including televisions, computer monitors, LCD screens, and digital camera sensors.13 A screen or series of pixels using three primary colors—red, green, and blue—are added together in various ways to reproduce a broad array of colors. RGB can be represented as an 8-bit color (representing 256 colors most frequently used for screen-based images), 16-bit, or 24-bit color (representing 65536 or 16777216 colors, respectively). Sixteen-bit color has become the minimum standard for Photoshop or prepress images, and sRGB is the standard color profile for images that will be viewed on a screen or sent via the web. sRGB provides the best color accuracy for images viewed only on a screen, but it does not have the wide color gamut of a 16- or 24-bit Adobe RGB file and, therefore, should never be used when creating or saving a master file.
An important note on color and monitors: One of the most problematic aspects of working with digital files is the lack of industry standards for quality and accuracy of color representation across equipment. Although FADGI aims to address many of these issues, users still face numerous technical hurdles in managing the color accuracy of files. Computer monitors in particular are extremely unreliable in their display of both color and brightness levels. An image file can appear differently when viewed side by side on different monitors. To further complicate the issue, Apple and PC platforms use different display gamma settings as their standards (gamma is the numerical term used to describe the brightness of an image). Apple suggests using a gamma value setting of 2.2, whereas most PC monitors should be set to a gamma value of 1.8. This difference in gamma value can cause images to display either darker or lighter, depending on the type of monitor being used, and lightness and darkness inevitably impact how colors appear. This shift in appearance is often incorrectly blamed on poor file quality rather than the accuracy of the display. To better understand the problem, it is important to understand the basics about gamma.
There are three types of gamma involved in digital images:
How we perceive an image on a monitor is determined by the gamma setting of the monitor, quality of light in the room, the make, model, and age of the screen. It is extremely important for anyone who works with digital images to know how to calibrate their monitor on a regular basis. Monitors that are capable of extremely accurate calibration are available for specialty industries, such as medicine, where there is a demand for a high degree of precision and the funds to support the high cost of such equipment. Some specialized companies also make very good quality self-calibrating monitors for photographic imaging needs, but they do come at a much higher cost than the standard PC monitor. This brings us back to the importance of having a color checker in each image. The color data contained within digital files and their numerical values do not change just because they are viewed on different displays. A photographer can use the individual swatches on a color checker to confirm the accuracy of the numerical data by testing it with the eye dropper tool found in Photoshop. The resulting numerical readout will confirm if a perceived color issue is originating in the file data or it is caused by a monitor.
When determining what storage method is right for a given situation, consider system security, asset lon gevity, user accessibility, and the budget. For photographs that are to be used for in-house documentation, a combination of on-site or cloud-based servers may be an appropriate storage method. If servers are not an option, a redundant array of inexpensive disks (RAID) system with secondary back up RAID can be used instead. A RAID is a system developed whereby two or more disks are physically linked together to form a single logical, large capacity storage device that offers a number of advantages over conventional hard disk storage devices—superior performance and improved resiliency. One of the techniques employed in a RAID system is mirroring. This was the first real implementation of RAID, typically requiring two individual drives of similar capacity. One drive is the active drive and the secondary drive is the mirror. The technique provides a simple form of redundancy by automatically writing data to the mirror drive when it is written to the active drive.15 This duplication of data makes a critical loss or corruption of all of data less likely.
Because digital data is prone to becoming corrupt, regular backups of images are always recommended. Master files of images and any important derivatives should be stored on a secure system with the back-up copies stored in another location. As technology changes, the methods of storage will need to be upgraded or changed completely. For example, DVDs used to be the main method of digital storage, but as technology improved, disk technology has changed, and disks no longer can be read by many computers. Regardless of the storage method chosen, be mindful of changes and upgrade as needed. Otherwise, there is a risk that the storage method will become obsolete and unusable.
A crucial decision before photographing objects is determining who will do the work—a freelance photographer or a staff photographer. There are many types of photographers—commercial, fine art, and fashion to name a few. In addition, photographers come with a wide range of experience and expertise. Most object photographers are freelance or independent photographers and their clients consist of museums, galleries, and private collectors. When deciding to hire a freelance photographer, several issues must be considered.
Finding a photographer who has the studio experience necessary to photograph cultural objects and artwork and can address the institution’s needs is important. If working alone, it is critical that the photographer know how to safely handle the objects. Photographers who regularly work for museums or galleries will probably be familiar with implementing FADGI standards in their workflow. The photographer should be responsible for editing, color management, metadata entry, and proper file formatting. With freelance photographers who do their own postproduction work, it is important to define the extent of this work up front. Will the institution be able to view and select images before they are processed? Who is responsible for the naming and metadata and how will the final images be delivered?
Any photographs done by a freelance photographer should be considered “work for hire,” meaning that the museum is the sole copyright owner. Under US copyright law, this arrangement must be stated in writing and agreed to by both parties. If it is not, the photographer may claim to own the copyright and distribute the copies of the photographs. Any agreement should include the following language:
Work for Hire: You agree that all original works prepared by or for you in the performance of the services for the Sample Art Museum shall be “works made for hire,” and the Sample Art Museum will own such works and all copyright and all other intellectual property rights therein. For any original works of authorship prepared by or for you in the performance of this agreement that, under the copyright laws of the United States, may not considered works made for hire, you agree at the request of the Sample Art Museum to convey and assign all copyright interests that may subsist in any documentation developed by you to the Sample Art Museum. This provision shall survive the termination of this agreement.
Contracts for freelance photographers should also specify if and how the photographers can use images as part of their portfolios. Will the photographers link their own website to the museum web-sites or provide a private link to clients? Is it ok for them to post these images on social media? Such details are particularly important if an artwork is held in copyright or is by a living artist. It should not be assumed that a photographer understands the intricacies of copyright as applied to the museum or individual works, and therefore, it is best to clarify any details concerning image use in the contract.
Details concerning the expectations for freelance photographers to use their own equipment or the use of museum equipment should also be clearly outlined. Most freelance photographers will bring their own cameras, laptops, and lights to a photo session. However, there are some large-sized accessories (e.g., paper backdrops, tables, special mounts) that may not be practical to transport and therefore may be provided by the museum.
The final issue is whether the museum will require the photographer to carry liability insurance. For example, if a photographer is hired by the museum to take pictures of an exhibition, and trips over the power cord of one of the lights and is injured, who is responsible, the museum or the photographer? Accidents will happen, and part of the museum’s risk-management strategy should be to determine whether responsibility lies with the institution or with the freelance photographer.
Although most of the issues related to hiring free-lance photographers also apply to staff photographers, there are differences. A freelance photographer will require an office or studio workspace, all the necessary photography equipment and a computer. A staff photographer has the distinct advantage of providing a consistent level of service and being available to respond to institutional needs as they evolve. Because the staff photographer is an employee, all the photographs are the property of the museum, and the institution would supply the necessary liability insurance.
Object photography can play an important role in an institution, from documenting the collection in marketing and public relations. It is important to determine the role that object photography will play in the institution. Whether a museum chooses to use the services of a freelance photographer or employ a staff photographer, the goals and uses of the museum’s photography program must be part of a well-defined institutional strategic plan to ensure that the money invested in object photography goes toward the fulfillment of the institution’s mission. •
1. Available at: http://www.digitizationguidelines.gov/.
2. Available at: http://www.digitizationguidelines.gov/.
3. Rick Matthews, “Digital Image File Types Explained,” Wake Forest University. Available at: http://www.wfu.edu/-matthews/misc/graphics/formats/formats.html (accessed November 24, 2008).
4. Per Christensson, “Raw file definition,” TechTerms. Available at: https://techterms.com/definition/rawfile (accessed January 7, 2019).
5. Per Christensson, “TIFF definition,” TechTerms. Available at: https://techterms.com/definition/tiff (accessed January 7, 2019).
6. Per Christensson, “JPEG definition,” TechTerms. Available at: https://techterms.com/definition/jpeg (accessed January 7, 2019).
7. Judy Louff and David Stephenson, “PNG (portable network graphics),” Techtarget. Available at: https://searchmicroservices.techtarget.com/definition/PNG-Portable-Network-Graphics (accessed January 7, 2019).
8. Thomas Rieger, ed., Technical Guidelines for Digitizing Cultural Heritage Materials: Creation of Production Raster Image Files, Federal Agencies Digitization Guidelines Initiative (FADGI), September 2016. Available at: http://www.digitizationguidelines.gov/guidelines/FADGI%20Federal%20%20Agencies%20Digital%20Guidelines%20Initiative-2016%20Final_rev1.pdf.
9. Wikimedia Foundation, Inc., “ICC Profile.” Available at: http://en.wikipedia.org/wiki/ICC_profile (accessed November 24, 2008).
10. International Color Consortium, “About ICC.” Available at: http://www.color.org/abouticc.xalter (accessed January 10, 2019).
11. Adobe, “About color profiles.” Available at: https://helpx.adobe.com/acrobat/using/color-profiles.html (accessed January 10, 2019).
12. Wikimedia Foundation, Inc., “Image: Colorspace.png.” Available at: http://en.wikipedia.org/wiki/Image:Colorspace.png (accessed November 24, 2008).
13. Wikimedia Foundation, Inc., “RGB color model.” Available at: http://en.wikipedia.org/wiki/RGB_color_model (accessed November 24, 2008).
14. Jo Plumridge, “Gamma: Why monitor calibration is essential,” Lifewire. Available at: https://www.lifewire.com/what-is-gamma-493590 (accessed January 7, 2019).
15. PCTechguide.com, “RAID tutorial—the benefits of using RAID.” Available at: https://www.pctechguide.com/how-to-set-up-a-raid-array/raid-tutorial-the-benefits-of-using-raid (accessed January 8, 2019).
Thanks to Scott Hankins.
