5 Postprocessing and Digital Asset Management
This chapter discusses technical considerations for optimizing image quality after the time of capture, as well as methods for organizing an image library, backup methods, and techniques for speeding workflow such as use of presets. Detailed discussion of video formats, compression, and archival solutions follows, with an attention to characteristics that should be respected when choosing an endoscopy and video archival system.
color management, compression, encoding, endoscopy, file format, postprocessing, preset, video, workflow
Postprocessing and Digital Asset Management for Photography
There are several steps that occur between the time of image capture and display of a finished image, and it is important to take control of this whole process for the best results. It is also important to develop robust systems to sort, store, and protect the entire library of images. Optimizing the postprocessing workflow not only saves time, but also improves results.
Prior to taking any pictures, there are a few important preparatory steps. Use only high-quality, high-capacity memory cards, which are not only faster and more reliable, but also carry more robust warranties. If your camera has multiple card slots, set it to record a copy of the image to each card (instant backup). Format the memory card with the camera immediately after the images from the previous shoot have been stored safely. Set the camera to RAW mode, lossless compressed, if available, to allow the most flexibility for controlling light and color later. Ensure the date and time are properly set on the camera, as this information will be stored with the rest of the image metadata. Finally, ensure that you have extra fully charged batteries, and consider obtaining a second camera in case of a malfunction.
During the shoot, there are a few tips and tricks to facilitate later image processing. First, make a patient placard with their name and pertinent information. The first image from the shoot is of the patient holding the placard below their chin (Fig. 5.1). It is also helpful to always shoot the images in the same sequence. If an image is obviously flawed, simply delete it and retake it. If an image is of questionable quality, take several copies. Review them all on a large monitor, and select the best to retain. The best way to obtain a great final image is to start with excellent images at the time of capture.
At the end of the day’s shooting, the images are copied from the memory card to an external hard drive, and then processed using one of several software programs (Fig. 5.2). The author’s personal preference is to use Adobe Lightroom for the vast majority of routine work, with Adobe Photoshop used for certain specific tasks such as deliberate image modification. Other packages such as Capture One, Photo Mechanic, or Perfect Browse can also be used. It is important to develop a folder structure and naming conventions to keep the images neatly organized and easily accessible. The author’s recommended method is to store the RAW images in a master folder, and create individual folders for each patient, named “Lastname, Firstname, Record Number–operation.” The images are renamed with the patient’s name and the image series, e.g., “Lastname, Firstname, Record Number–Rhinoplasty Series Image 1.” Institutional policies on record-keeping and patient identifiers should be respected. Keywords can be added to the metadata to facilitate later searches for specific images. Finally, labels can be applied to images for a teaching file or other special use, and duplicate copies of selected images can be placed in an “Interesting Images” folder.
Fig. 5.2 Behind-the-scenes view of postprocessing
As medical photographs exist for accurate documentation, editing of their content is not only forbidden, but also counterproductive. However, certain processing of the image is required, including careful adjustment of global parameters such as brightness, contrast, white balance, and saturation, with caution not to introduce errors or inaccuracies (Fig. 5.3). A properly calibrated monitor is required. The sliders in the Lightroom “Basic” panel can all be adjusted small amounts as needed, but with proper camera and light setup, there should be little need for this. A small amount of sharpening and automatic lens profile corrections should be applied. The image can be cropped and straightened if needed, and it is often helpful to shoot the image a bit wide and then crop to the exact anatomic boundaries specified. Special effects filters are not to be used, nor is localized editing such as blemish removal or dodging and burning. Once the images have been optimized in Lightroom, they are saved as maximum-quality JPEGs in the patient’s folder and can be printed if desired.
If using Lightroom, a great time-saver is the use of an Import Preset. All of the commonly used settings can be saved and automatically applied to all images as they are ingested into one’s catalog. This has the added advantage of producing standardized results. Similarly, presets can be developed for almost any function of the application and can facilitate essentially any repeated task.
Color management is an incredibly complicated topic to master, but the basic concept is to maintain accurate depiction of colors throughout all steps of image creation, processing, and display. This must be maintained across platforms and during subsequent examinations, so as not to confuse poor color calibration for subtle anatomic changes. In the postprocessing setting, this means the use of standardized color profiles and calibrated display monitors. Several tools exist to perform this automatically, but similar results can also be obtained manually.