(Editor’s note: Reuters.com asked Gary Hershorn, News Pictures Editor for North America, to discuss some of the tools photojournalists have used in the past — and what they use now — to produce pictures. On Monday, Reuters withdrew all 920 photographs by a freelance Lebanese photographer from its database after a review showed he had altered two images. You can see the images and reactions from readers here. Reuters, also the publisher of this report, tightened procedures for photographs from the conflict between Israel and the armed group Hizbollah and apologized for the case. You can read the company’s statement here. You can send a comment to Hershorn from the link below and read his interview with NPR today here) Photojournalism tools News photographers routinely process images using Adobe Photoshop software. But there has been a basic premise in the world of photojournalism that what was allowed in making prints in the pre-digital days of darkrooms is all that is acceptable today. Back in the days of the darkroom, we used very basic tools to develop prints. In black and white printing, the contrast of a picture was controlled by a paper’s grade. The higher the number of the paper, the higher the contrast. In the wire agency darkooms I’ve worked in, we typically used grades 3,4 and 5. We allowed “dodge and burn” to lighten or darken areas. A dodge tool was made by taping a small piece of cardboard the size of a quarter onto a paper clip. A burn tool was a piece of cardboard the size of an 8×10 sheet of paper with a hole in the center. If a print had dust spots caused by a dirty negative, we used Spotone, a photographic paint that was dabbed onto a print with a very fine paint brush to eliminate the unsightly marks. One other tool that was allowed when printing color pictures was changing color balance. This was done by placing filters between the light source of the enlarger and the paper that the image was being printed on. When we moved to scanning negatives and then to shooting digital, we began using Photoshop. This program allows us to do the same things we did in the darkroom. Changes in contrast, dodging and burning and color balance are now done with software. The most controversial tool in Photoshop that we use is the cloning tool. The only accepted use of this tool is to clear dust from the image. We have a zero tolerance policy when it comes to using the cloning tool to change content, and by that we mean removing something that exists in a photo, moving or replicating it or adding to a photo.The tools we use in Photoshop are levels, curves and saturation for changing contrasts; and, color balance to bring the image back to the way the natural eye would see the color. Here is what we tell our photographers in the Handbook of Reuters Journalism.Photoshop is a highly sophisticated image manipulation programme. We use only a tiny part of its potential capability to format our pictures, crop and size them and balance the tone and colour. For us it is a presentational tool.The rules are no additions or deletions, no misleading the viewer by manipulation of the tonal and colour balance to disguise elements of an image or to change the context.Photoshop is a powerful image processing program with many more tools to help photographers produce the best quality image they can for the type of photography they do. There is not a Photoshop program for use by news photographers and another for advertising, where image-changing is tolerated. What we in the news photo community need to regulate is what tools are used for photojournalism and what are not.