Digital camera technology captures an image on a CCD array through the optics of a photographic camera.
The other way is the use of laser scanners, which offer maximum resolution at a premium price, or charge-coupling device (CCD) scanners which are widespread and less expensive. Most of the radiographs are obtained in the traditional way, and the use of a digital camera is one way of getting hard-copy radiographs into digital format. Radiologists should find that image editing can be carried out very rapidly once the basic steps are learned and automated.EVEN THOUGH DIRECT DIGITAL IMAGING and a picture archiving and communication system (PACS) are already available in many radiology departments, hard-copy radiographic images are still present in every department. Editing and annotating images before they are inserted into presentation software is highly recommended, both for convenience and flexibility. Final file size for incorporation into computerized presentations is about 10-100 Kbytes (8-bit, single-layer, gray-scale, high-quality JPEG ), depending on source and intended use. Final file size for gray-scale cross-sectional neuroradiologic images (8-bit, single-layer TIFF at 300 pixels per inch) intended for publication varies from about 700 Kbytes to 3 Mbytes. Use of the smallest file size necessary for the purpose at hand is recommended.
Converting an image to 8-bit gray scale is the first editing function. The Actions palette is a menu of user-defined macros that save time by automating an action or series of actions. The History palette may be used to undo a step or series of steps. For basic editing of gray-scale cross-sectional images, the Tools palette and the History/Actions palette pair should be displayed. The authors introduce Photoshop 6.0 for radiologists and demonstrate basic techniques of editing gray-scale cross-sectional images intended for publication and for incorporation into computerized presentations.
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