20.05.10
Guy Gowan Answers Your Photoshop Questions
Guy Gowan is a legend in the world of digital imaging, work flow and manipulation. His seminars and DVDs sell out, he is constantly besieged by questioning followers, and his unique approach and opinions set the agenda for manufacturers worldwide. Each month, he answers the questions you need answered. So let’s click and drag with Guy Gowan.
Q.As a student, I am unsure of the correct process when retouching an image, is there an order that I should follow?
A. Yes, there certainly is and the order will be the same for a professional or a student. You’d be amazed how many people don’t use a logical order to process their work! The logical order would be if you shoot a RAW file, you can fine tune the exposure and you’d do that in the RAW converter; you could use the exposure slider or the recovery slider. Then when the image is in Photoshop you’d do levels. If you shot a JPEG to start with, you would use levels to micro adjust the exposure, then you would do your colour balancing, which is the same as changing colour temperature in the RAW file, or you could do this in Photoshop afterwards. (This is just changing the overall colour temperature of the image and isn’t the same as colour correction, which comes later.) Then you apply your contrast to add shape to your image, then you do colour correction – a colour treatment where you enhance all the colours in the spectrum to give your image the look and feel you want. After all that, generally at the end of the process, you apply sharpness. Once you are at this stage, you have the global version of the image and this is where you may want to apply retouching techniques, such as brightening eyes, teeth, cut-outs, extreme characterisation of the image and so on. So, to process an image to a good commercially acceptable standard, here’s the order I’ve always followed: exposure adjustment/levels, colour balancing, contrast, colour enhancement and sharpness. If you stick to that order, you don’t end up going round and round in circles wasting your time and perhaps losing your sanity!
Q.What is moiré exactly, and how can you remove it from an image?
A. Moiré is an area inside a shot that has a fine mesh. It occurs when you shoot fabrics – veils at a wedding, men’s check suits, net curtains, buildings, anything with parallel lines of contrast. It happens when the mesh in the object is conflicting with the mesh in your sensor. We came across this regularly back in the days of scanning. Scanning a transparency meant you often saw acute moiré on images because of the way the machine scanned the transparency in parallel vertical lines. Our solution back then was to physically rotate the transparency by 30 or 45 degrees, which shifted the moiré into the blue channel or removed it completely. If you shift any moiré into the blue channel, this generally means you are not removing any detail as the blue channel is just there for colour. So one option could be to rotate your camera by 30-45 degrees (use a wide-angle lens to compensate for the reverse rotate and crop) when you are shooting an image where moiré is likely. Nowadays, I prefer to use post production techniques as I don’t always shoot all my own images; I’m often given them with problems, so my own solution is to channel swap. I go into Photoshop, click on red, green and blue and find out which channel doesn’t have the moiré, and then duplicate this onto the channel that does have the moiré. You will have to do a bit of manipulation with curves to get the new colour to match the original colour, but I have always found this to be the best solution to solving moiré in an image. You will need to learn multiple options and methods of colourising the repaired area, because sometimes you have to go from one extreme to another. In my experience, channel mixing is the solution to post production moiré fixing, I’ve never had an image on which it didn’t work.
Q. How do you create black and white photos with the isolated colour creative effects? Is that Corel Painter? Or is it something that can be done in Photoshop?
A. Firstly, you don’t need Corel Painter for anything. Yes, it can be done in Photoshop in a thousand different ways, all I can do is tell you my way. My way starts off with never converting into a black and white or a greyscale image, because in doing so, you are throwing away the colour data. My black and white method is to use a layer that sits on top of the image, which retains the data but converts the image to black and white. Now you have a mask on that image and you can brush through that mask to say you want certain parts of the layer to be colour. What you need to remember now is the thing that makes a good black and white is contrast, and you need a lot of contrast to make a good black and white. But you only need a little contrast in a colour image, in fact only about half the amount that you need in a black and white image. You need to understand that the part of the mask that deals with the colour elements needs to have a separate contrast mechanism for that as well as one for black and white. It’s easy to do, but not easy to do in a convincing natural way, as it is the independent contrast that makes it work. This is covered in great detail on our website www.guygowan.com
Q. Banding is sometimes an issue in my images and I usually end up scrapping them as I can never seem to deal with it in Photoshop. Is there any failsafe method for taking it out of an image?
A. Banding has been a problem for graphic design over the last 20 years. If you work in Photoshop, Illustrator, InDesign or QuarkXPress from a design perspective, creating very smooth gradients has been a major problem in postscript. Photoshop has dealt with this in different ways over the years. In the early versions of Photoshop, there was little or no banding, but it crept in over the years and, as Photoshop evolved, somewhere between V1 and V3, an option called ‘Dither’ was added to the gradient tool. Banding is definitely a problem and it is very difficult to get rid of, so what you tend to do is mask it, not with a physical mask of a layer or an alpha channel, but you optically mask it by dithering. Banding is often wrongly perceived as something Photoshop is doing to an image, but in my opinion, this isn’t the case. When I do my retouching and see banding in my file in Photoshop, I go back to my original RAW file to make sure, and I will generally see a faint residue or element of the banding in the original image. Then I usually enhance that contrast or add contrast to the banding so that it’s more visible in the final image. You either remove the contrast in a particular area, say a sky or a shallow gradient area, or apply a noise to the image afterwards (a bit like the principle of unsharp masking, where sharpness is applied, but not so much that it’s actually visible in a distracting way). I apply a noise to all my images now. It’s a film-style texture which masks out 90% of all banding and gives them an organic, natural texture. Masking is the best method to achieve this.
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