Resizing PDI images

Instructions for some image editing programs:

Note: if you want to produce images for a 1024 x 768 AV rather than 1600 x 1200 you will want to use 1024 for width and 768 for height.


  1. Open your image in PS. If it is a 16 bit tiff change it to 8 bit, if it is a jpeg – don’t worry – jpegs are 8 bit, so you can ignore this bit. Select Mode - 8 Bits/Channel from the menu.
    Photoshop - change colour depth
  2. To change the pixel size of your image go to the menu bar and click on Image - Image Size...
    Photoshop - choose resize option

  3. This will bring up a box that will allow you to change the pixel size, either by width or height.
    Photoshop - resize dialog box
    • If your image is in landscape format (i.e. wider than high) then you want to set the width to 1600.
    • If you image is in vertical or portrait format (i.e. higher than wide), then you want to set the height to 1200.
    • Leave the ‘Resolution’ setting at its default of 72.
    • Most likely you will be reducing the pixel size of a larger image. You should use the drop down menu at the bottom of the box, and select ‘Bucubic Sharper’. If the image is already less than 1600 pixels wide and 1200 pixels high, then you probably shouuld not enlarge it! Submitting it as is will be fine. Enlarging an image is not generally a good idea since it will lose quality.
    • Click the OK button to actually resize the image.
  4. After you have resized the image, it may look small on your screen. Press Ctrl-0 (zero) and it will be displayed so that it fills the available screen space.
  5. The image is now the correct pixel size and should be renamed and saved as a separate file.


  1. Open your image in IrfanView
  2. Select Image > Resize/Resample from the menus
  3. In the dialog box:
  • Make sure the "Set new size" radio button is selected and that the "Preserve aspect ratio" checkbox is ticked
  • If it is a landscape format image, enter 1600 in the Width box, if it is a portrait style image, enter 1200 in the Height box - the other box will be filled in automatically
  • Make sure the "Resample (better quality)" option is selected in the bottom-right portion of the dialog and that "Lanzos (slowest)" is selected as the filter - this will give you the best quality resize
  • Click the [OK] button

Irfan view resize dialog

The image will be resized. You probably won't notice any change in the display! You can check it has actually been done by selecting Image > Information from the menus.

IrfanView info

Save the resized image as a .jpg format file in the normal way.


  1. Make sure you have your image open in GIMP
  2. Select Image > Scale Image ... from the menus
  3. In the dialog:
    • Make sure the chain icon connecting the Width and Height boxes is as shown - this will preserve the aspect ratio. If it shows a broken chain, click on it to toggle its state.
    • Make sure the units are "px" (pixels) as shown - if not select this option in the dropdown
    • If your image is in landscape format, enter 1600 in the width box, if it is a portrait style image, enter 1200 in the Height box. Click in the other box and the other dimension will be filled in automatically
    • Make sure the Quality Interpolation "Cubic" is selected - this gives the best quality results, although it takes the longest to process!
    • Click [OK]

GIMP resize dialog

The rescaled image will be shown and will probably appear rather small in the centre of the image window. Press Shift-Ctrl-J (or select View >  Zoom > Fit Image in Window from the menus) to zoom the image so that it fills the image window.

Export the rescaled image as a .jpg formatted file in the normal way.