Image Editing

From TSG Library of Knowledge

There are endless ways to change an image to make it look just as you want and many of them are quite easy. On this page, you will find mini tutorials for adjusting and editing your photos inside your preferred image editor.

Filters and Adjustments

Filters are refinements made to the entire image, like changing it's hue or contrast. The word comes from the actual filters placed in front of camera lenses to change the appearance of the photo. Adjustments, similar to filters, are refinements that change the entire image, but they change different things, like brightness, exposure, shadows, and highlights.

An example of contrast changes. The left images are having their contrast progressively decreased while the ones on the right are having their contrast progressively increased.

Brightness and Contrast

Brightness and contrast are two of the most used image adjustments and they are often used together when brightening or darkening an image, so you will often find them together in the same dialog or window. Brightness adjusts how close or far away pixels in the image are from white or black, and contrast defines the difference of color between pixels. The image editing application you are using may have an auto brightness and/or contrast menu item, which can help tremendously when editing large batches of photos, but be warned, it may not give the desired result.

A typical brightness slider, this one from Adobe Photoshop.

Adobe Photoshop

To change the brightness of an image in Photoshop, go to Image > Adjustments > Brightness/Contrast and adjust the top slider for brightness and bottom for contrast. You can toggle the adjustments being shown on the image by checking or unchecking Preview. When you are satisfied with your changes, click OK.

Irfanview

In Irfanview, go to Image > Color Corrections. There you will find the brightness slider (on the left) and the contrast slider along with a whole host of other tools. Set the sliders to your desired value and click OK.

Paint.NET

To change the brightness and contrast, go to Adjustments > Brightness / Contrast and move the sliders or place a specific value. To rest a slider, simply click Reset. When finished, click OK.

Mac OS X Preview

You can easily edit the brightness and contrast settings in the seemingly primitive Preview application, included with all Macs. Go to Tools > Adjust Color and you will find the second and third sliders control brightness and contrast, respectively. To regress a change, go to Edit > Undo or to Reset All to return all the color adjustment changes. To keep your changes you must save the file (File > Save).

Pixelmator

In Pixelmator, go to the Image menu and select Brightness and Contrast. Drag the sliders to get the preferred result and click OK.

Hue and Saturation

Another two adjustments often found together, hue and saturation affect the color in an image. Hue changes what color the pixels are and saturation changes how much color there is or how intense it is. When an image is desaturated, it means all the color is taken out and it is now a black and white (technically grayscale) image.

Adobe Photoshop

To adjust Hue and Saturation, go to Image > Adjustments > Hue/Saturation, there, you can change the hue and saturation with the first two sliders and also perform more advanced functions. You can change the lightness (making each of the pixels brighter or darker, different than brightness) by sliding the third bar and also change the hue, saturation, and lightness of individual hues by changing the Edit: drop-down menu.

Irfanview

Paint.NET

In Paint.NET, go to Adjustments > Hue Saturation and change the settings. Similar to Photoshop, there is a lightness slider to make the image lighter or darker.

Mac OS X Preview

In Preview, you cannot edit the hue, however you can edit the saturation and even change other color features like color temperature and tint. Go to Tools > Adjust Color and move the Saturation slider. To regress a change, go to Edit > Undo or to Reset All to return all the color adjustment changes. To keep your changes you must save the file (File > Save).

Pixelmator

Levels

Adobe Photoshop

Irfanview

Paint.NET

Mac OS X Preview

Pixelmator

Size and Position Changes

Cropping

Cropping is selecting part of the picture and making it the whole picture. For example, if you had a picture of a person and there are things on the sides that detract from the picture or you just want to zoom in more on them then you would crop it.

Left: Changes in hue
Right: Changes in saturation.