Picture this: Photoshop loses mystery for radiologists

Digital manipulation of images plays a key role in development of multimedia presentations for teaching and conferences. Taming commercially available tools for easy use by radiologists is therefore inspiring considerable effort.

Two recent papers report on strategies to demystify Photoshop for the nonexpert user.

Radiologists at the University of Louisville School of Medicine, led by Dr. Ronald D. Caruso and Dr. Gregory C. Postel, demonstrate basic techniques of editing gray-scale cross-sectional images intended for publication and for incorporation into computerized presentations (J Digit Imaging 2002 Nov 6; [epub ahead of print]). This is a follow-up to their earlier article (Radiographics 2002;22:993-1002) on image editing in Adobe Photoshop.

"Photoshop is a powerful tool for rapidly editing and annotating images for teaching files, presentations, Web postings, and publication," Caruso said.

Photoshop gives the radiologist maximum control over the appearance of the image and permits easy alteration of image file type, resolution, and file size.

"Its automation is particularly useful," he said.

In another report (Radiographics 2002;22:981-992), Frank M. Corl, a research associate in radiology at Johns Hopkins University School of Medicine, offers five basic steps to digitizing images and preparing them for publication and computer presentation:

?scanning
?correction
?editing and labeling
?saving files
?producing final output

"These steps can be completed with commercially available hardware and image manipulation software such as Photoshop," Corl said.

The higher the quality of the original scanned image, the more image data there will be to edit. A good image cannot be created from an inferior scan, he said.

"The most important functions for properly scanning images are size, resolution, and color," Corl said.

Resolutions of 300 ppi and 72 ppi should be used for print publication and computer presentations, respectively. The higher resolution image has the larger file size. The scanned image should be saved as a TIFF (tagged image file format), which is an uncompressed file type used for printed images, he said.

JPEG format compresses the size of the image file but also reduces image quality, according to Corl. The JPEG format is a good choice if a small file size is needed, as in Web and PowerPoint presentations.

"If the user needs to save an image as a JPEG file, the image should be edited first and then saved once in JPEG format," he said. "With Photoshop, the user can rotate and crop an image; adjust its brightness, contrast, and color; remove unwanted patient information, dust, and scratches; and add text and symbol labels to enhance images for teaching purposes."