Snapshot (editing)

A Snapshot is a record of the current image state while you’re editing it. You can create a Snapshot in Photoshop or Lightroom when you reach a point that you think you might want to return to during editing. You can save a number of Snapshots to quickly compare different editing steps.


‘Resizing’ and ‘resampling’ sound the same but they’re not. ‘Resizing’ an image means usually means changing the size at which it will be printed, not changing its actual pixel dimensions. So for example you can ‘resize’ a photo to print it as a 6″ x 4″ or a 12″ x 8″. The only thing that changes is the number of pixels per inch in the final print. Some programs blur the distinction between ‘resampling’ and ‘resizing’ so it’s important to make sure you understand what they’re about to do.


Changing the pixel dimensions of a photo, usually to reduce the file size for sharing or online use. Resampling is irreversible because it changes the pixels in the photo. If you resample an image down to a smaller size, there’s no way to return it to its original form – the pixels discarded in this process can’t be restored.


A basic image adjustment found in most image-editing applications. You can use Levels to inspect the image histogram and move the black point and white point sliders so that there’s a full range of tones from solid black to brilliant white.


A way of adjusting the colours in an image – the Hue adjustment shifts the colour along a continuous spectrum, while the Saturation adjustment changes its intensity. For example, you can shift the hue of leaves away from yellow towards blue and increase their saturation to make the leaves look ‘fresher’.


Many programs can store a ‘history’ of all the editing changes you’ve made since you opened an image. Using this you can check what you’ve done and even backtrack to an earlier image state if you realise you’ve made a mistake. Some programs can store the history as part of the saved image file, while non-destructive editors like Lightroom will store it indefinitely as part of the image’s adjustment metadata.


Tool used to adust the contrast and brightness of an image without ‘clipping’ highlight or shadow detail. The shape of the curve affects the brightness and contrast of different tonal ranges in the photo. A classic ‘S-shaped’ curve is steeper in the middle, increasing midtone contrast, and flatter in the shadow and highlight regions.


Trimming images to remove unwanted detail at the edges or make them fit the aspect ratio of screens or specific printing papers or to improve the composition of a photo.

Batch processing

Applying the same image adjustments to a whole batch of photos. For example, you might choose a black and white conversion style and apply it to all the photos from a particular shooting session. Batch processing can save a lot of time, but only if all the images will benefit from the same settings.

Adjustment layer

A special type of layer in image-editing software which is designed to hold adjustments rather than other image layers. It’s a way of ‘stacking’ a series of adjustments to an image without affecting the image layer itself.