Image Optimisation Techniques

We will cover all of the following techniques in this course. This is quite a lot of material, but understanding how to use these can really improve the basic quality of an image, either its composition or its visual appearance.

Managing Composition

The techniques in this section let you modify the basic composition of an image. Often your initial concern, particularly outside of the studio, will just be to get the shot! Don't worry, you can recompose the image on the computer later.

Rotation

This can be by a set amount (usually 90o), when it is used to get an image in the correct aspect. That is, when you load a portrait image into an editor it sometimes appears landscape and needs to be rotated by 90o to get the correct aspect.

Secondly, you may need to rotate an image by a small amount to correct the alignment of a horizontal or vertical element such as the horizon. Usually it will take some experimentation to get the correct angle for the rotation.

You can find more details about image rotation techniques here...Here

Cropping

This technique involves selecting a specific portion of an image for use and removing the remaining, unwanted parts. It is done to emphasize the composition. This technique can be done with a regular selection tool, but most programs also provide a dedicated cropping tool.

You can find details of cropping here...Here

Exposure and Colour

Often it is necessary to improve the overall tonal balance of an image. For example, a photo taken on a long telephoto lens on a dull day may look a little flat. There are a wide range of tools that can be used for this task. The techniques discussed in this section allow you to modify the exposure of an image after it has been taken, or to modify the final colour balance. However, you need to be careful, as applying too much of these techniques can make an image look very unnatural.

Brightness & Contrast

The most basic tool that you can use simply allows you to adjust the brightness and contrast of the image. This can allow you to correct for minor exposure errors in the original image.

You can find more details about this control here...Here

Levels

This technique provides a more technically exact way of improving the brightness and contrast of an image by working with the tonal graph (histogram) to ensure that the image has a fairly even spread across the whole luminance spectrum.

You can find more details of this tool here...Here

Curves

This technique provides another way of working with the histogram, giving more precise control over which areas of the spectrum are amplified or attenuated by adjusting the curve of the graph directly.

You can find more details of this tool here...Here

Colour balance

This technique allows you to modify the colour balance in your image by adjusting the relative levels of the complementary pairs of colours red/cyan, green/magenta, blue/yellow.

You can find more details of this tool here...Here

Hue & Saturation

With this tool you can modify the tone and level of specific colour channels in the image as well as the overall settings for the image. For each of the primary and secondary colour channels you can adjust the hue, saturation and lightness.

You can find more details of this tool here...Here

Repairing Problems

The techniques in this section give you tools to repair any imperfections in an image. For example, an unwanted jet trail in the sky that spoils the effect of the composition can be removed once you have the image on the computer.

Healing

This technique involves eliminating small blemishes or unwanted parts of an image by painting over them with adjacent background colour and texture.

You can find more details of this tool here...Here

Blurring

Blurring might not seem like an obvious technique for improving an image, but it can be used to smooth out slight differences in the image to make a region of colour look more uniform.

You can find more details of this tool here...Here

Sharpening

As the name suggests, this is the opposite of blurring. Sharpening an image makes the edges clearer and the details stand out. However, if you over sharpen an image the result can look very unnatural, so apply this tecnique with care.

You can find more details of this tool here...Here