Over its 20 year history, Photoshop has proven itself to be useful for many things. One of the main applications is photo manipulation. In fact, it's photo manipulation that is meant by the colloquial term "to Photoshop". But performing a successful photo manipulation is not as easy as it sounds.
So, whether you're new to the game or a seasoned photo changer, there's always room to learn and grow. I've put together a list of tips to make sure your photo manipulation skills are better than the rest.
1. It's All About Resolution
When working with images, think of pixels as the raw material for the media. They are like a paint tube for a portrait artist or a fabric bolt for a tailor. Any craftsman in his field will tell you that it is thrifty on raw materials. Photo manipulation is no different. Pixels tend to be stretched, squashed, tilted, and abused. The more that has to be done, the easier the task and the better the end result.
So how much do you need? A good rule of thumb is to work at a size of 150-200% of the final cut, and then resamplify the finished image down. Knowing the intended delivery medium is very important. Print media requires more resolution than screen displays. Most print jobs require a resolution of 300 dpi, while screen displays can be as low as 72 dpi. That's a big difference.
The risk of not using a high enough resolution image is that the latter can appear distorted, pixelated, or blurry. This problem is exacerbated when using photos from several different sources. Always try to make sure the images you choose for your photo manipulation projects are all of the same resolution. If not, start with the lowest resolution image and work your way up to the rest of the image.
2. Light and Shadow
One of the most important tasks in creating a trustworthy photo composite is that the lighting is consistent. If any element in the scene has distinctly different lighting, and therefore different shadows, that element will never seem to match its surroundings. This is commonly known as the "green screen effect" because it often occurs in TV and movies where the composed background has a much different lighting than the actors and actresses on the screen.
The best way to make sure the lighting and shadows for your photo manipulation are correct is to have a solid understanding of how light and shadow work in the real world. Light is a 3D element and casts shadows in 3D space.
Once you know the main light source for your scene, make sure any surfaces are lit or shaded from that light source. Then follow in doing this for each light source in the scene. It sounds like a lot of work, but it's not hard, and once you understand the visual geometry behind it, the task becomes a lot faster.
3. Put in Perspective
Second after light and shadow, the worst element of photo manipulation is improper scaling. Sometimes the exaggeration is intentional, and often that's the point of the piece. But when elements are inconsistent in scale, it can create a strange sense of something just "off". When that happens, it breaks the suspension of disbelief, and viewers instinctively know that the image is visually unbelievable.
The best method to ensure all elements are in proper scale agreement is to think about the perspective of an image. Identify the horizon and vanishing point, then make sure your elements align with these. Usually these concepts are associated with illustration and drawing, but they have very obvious applications for photo manipulation as well.
