PDI Guide

Preparing Projected Digital Images (PDI) for competitions

The Quick Guide

1. Resize your image so that its width is 1280 pixels or less, and its height 800 or less.
2. Make sure that your image is in the sRGB colour space.
3. Save your image as a .jpg file.
4. Put the images to be projected into a folder whose name is <Author’s first name> <Author’s last name>. Make sure that the filename of each image is its title.
5. Get the images to the competition secretary by email or flash-drive.

Folder and File Names for Club PDI Competitions

The images in an author’s entry must be contained in a single folder.

To set up a folder, assuming that your images are in ‘My Pictures’ (Windows) or ‘Pictures’ (Vista): display ‘My Computer’ (Windows) or ‘Computer’ (Vista); click on ‘My Pictures’ (Windows) or ‘Pictures’ (Vista);; click on ‘File’ at the top left of the window, and choose ‘New’ and then ‘Folder’ from the menu. A folder will appear called ‘New Folder’ and highlighted in blue. Right click on this new folder, choose ‘Rename’, and name it in accordance with the rules set out below.

The folder should be named <Author’s first name> <Author’s last name>. The author’s name derived from this folder name is used to credit the
author of the images during the competition.

Make sure that the filename of each image is its title. If necessary, right-click on the file name of an image, select ‘Rename’, and enter the title of the image.

Filenames must conform to the usual Windows conventions. Avoid punctuation marks and special symbols. Upper and lower case letters and digits are OK, along with space, underline, hyphen, single-quotes, exclamation marks and
parentheses. Note particularly that period and comma are not allowed. The file name shopuld not be more than 60 characters in length. The files must have the .jpg extension.

Mac OSX users need to be particularly careful to follow these Windows conventions.

Examples of typical filenames are:

1. Sleepy Head.jpg
2. Salisbury – South Isle.jpg
3. HMS Victory – Detail.jpg
4. Dawn at Martin Mere.jpg
5. ‘Missed It!’.jpg

Resizing images for Digital Projection (PDI)

To resize an image in most versions of Photoshop we can use Image> Image Size or Resize Image. Please note the names of commands vary between versions of Photoshop.

resizing_picThe screen shot shows the typical Image Size dialog box in Photoshop. Start by checking the Resample Image box, and choose Bicubic from the drop down menu. At the top we have the actual dimensions of the image in pixels. This was an 8 megapixel camera image. If necessary the units can be changed to pixels using the scroll down menus alongside. Note that the locks that link the width and height numbers are set by checking the Constrain Proportions box near the foot of the panel. This must be checked for the resizing process to work correctly for our purposes.

The resolution can be set at 72 or 96 pixels per inch, which displays the image at about normal size when viewed in Photoshop at 100% on your monitor.

Make your changes in the Width and Height boxes under the Pixel Dimensions heading. Don’t worry about the Document Size boxes. Don’t worry about the Scale Styles box.

The Easy Way: just try some numbers

The image frame on our projector is 1280 pixels wide and 800 pixels high. Not all projectors are the same; if you are preparing your image to be shown on a different projector, you should find out the size of its image frame.

Just type in 1280 in the Width box, and the number in the Height box will change to keep the same proportions. If the height figure is 800 or less then your resized image will fit within the frame. If the figure in the Height box comes out at more than 800 pixels, then type 800 in the Height box, and the figure in the Width box will reduce to less than 1280 pixels, to maintain the same image proportions.

Once you have a satisfactory combination with the width less than or equal to the 1280 and the height less than or equal to 800, click the OK button and then save your new image.

Alternatively: use the Crop command in Photoshop

A different approach is to crop your image in Photoshop before you start to manipulate it, so that it suits the aspect ratio of the projector. Our projector has an image aspect ratio of 8 wide x 5 high. Select the crop tool. Above your image, at the top of the screen, you’ll see two boxes labelled Width and Height. Just enter 8 in the width box and 5 in the Height box (you don’t need to put any units of measure – you are setting the proportions, not the size). This ensures that after you have finished preparing your image it will have the right proportions to fill the frame when it is projected. But you must not feel constrained by the aspect ratio – if your image demands a letterbox format it will display perfectly well, but there will be some black space above and below it.

Check and Save

Remember that the width must be 1280 pixels or less and the height must be 800 pixels or less. Once you have a satisfactory combination of height and width you should click OK.

Save a copy as a maximum quality JPG. Note that Photoshop (.psd) documents are NOT suitable for projection.