How to size for comps

How to Resize Images in Photoshop

Why Resize Images?

An image size of 1600 x 1200 has been set as a standard for all digital images submitted for display in club events.

However as with all manipulation processes, resizing carries a Health Warning i.e. it can damage your image quality. All JPEG images are compressed in order to save, so it follows that each open / process / save operation loses a little image information. Ideally all editing should be carried out using a 'lossless' file format; RAW, TIFF or Photoshop's own (PSD etc). The final process of saving for display should be the conversion to JPEG (JPG).

The image resizing process

  1. First, open a fully edited and 'ready to display' photograph in Photoshop. You can do this by (a) going to File->Open and selecting the photograph we want to edit:, (b) 'dragging and dropping' an image from your file manager, (c) using Adobe Bridge or you may have come straight from Lightroom.

  2. Go to Image->Image Size and you will be presented with the dialogue that shows the pixel dimensions. Make sure to check “Constrain Proportions” on the bottom. If your image is 'landscape' you should enter 1400 as the value (“pixels” should be selected next to it). As you type the width you will see that the height will automatically adjust to a smaller number, as long as the 'Constrain Proportions' box has been ticked. For a portrait image, tab to height and insert 1050.

  3. Resizing - fig 1a
  4. If you are using Photoshop CS you are also offered the opportunity to set the DPI. There is a lot of confusion over the DPI (dots per inch) setting that should be used. The DPI value you use to save your image does not matter. You can leave it at whatever value it is set at (72 is often the default from your camera) and you don’t need to change anything. The DPI value is only important for print – changing it will only add metadata to the file and will have no impact on how it is actually displayed on a monitor. However if a competition puts a file size restriction on entries, it may be as well to chose 72 dpi or similar to keep the megabytes down.

  5. The next task is to select a resampling method. On the very bottom of the screen you should see a dropbox with the following choices: Nearest Neighbour, Bilinear, Bicubic, Bicubic Smoother and Bicubic Sharper. I recommend the “Bicubic (best for smooth gradients)” one, because it does a great job in reducing noise without sharpening the image (which it already did). Click OK after you have completed all the above.

Now the image is probably much smaller in size. Noise should be completely gone as well (assuming it was not too noisy to start with), thanks to the Bicubic down-sampling method that we have used in the previous step.

  1. The final step is to Save the image. Ideally you should select File > Save As and create a new name for your image firstly because you will want to retain the original and also because Photoshop will offer you the option to select the JPEG quality. Choose a high quality option (10 or above).

Another way to resize an image using the Photoshop CROP tool

  1. Make sure your background colour is set to the colour you wish to be seen as the 'outside the frame' part of your image. If your image does not share the same ratio as 1600 x 1200 pixels there will be a border on at least two of the edges.

  1. Set the crop tool to unrestricted and insert 1600 px as the width and 1200 px as the height. The dpi does not matter. (N.B. even if your image is in portrait aspect continue with the same settings. The rules require that the height must not be more than 1200px, just the border will alter.)

  1. Open your fully edited and saved image into the working area and select CROP tool. If you are using Photoshop CS, the crop frame will appear centrally on the image and not extending beyond its bounds. (In Photoshop Elements you will have to apply the crop shape which you should fill as much of the image as you can without overlapping its bounds, then release the cursor).

  1. Select any corner and pull the crop area out until the part of the image that was outside the crop area is level with the cropping frame. This will have taken one side of the crop area into no-man's land. Now Select the diagonally opposite corner and do the same.

  1. Press accept (tick) and presto the job is done. Now save your image with a new name.