PDI Specifications

TPS runs several competitions for Projected Digital Images (PDIs) which are  images submitted as digital files for display on a projection screen using a computer and digital projector. Digital images can come from digital cameras, but also scans of slides, negatives or prints are acceptable. The guidelines below should be followed when preparing your images for submission.

PDIs should be entered using the online PhotoEntry system.  Full details of using the system can be found here.

1. All image files should be in JPEG (.jpg) format – this format is supported by all major imaging software applications, on all platforms (e.g. PC, Mac, Linux). Note the file extension must be .jpg, NOT .jpeg.

2. Image files must fit a 1600×1200 pixel canvas – i.e. they should be a maximum of either 1600 pixels wide and/or 1200 pixels high. Since images produced by a digital camera, or a scanner will typically be much larger than this, members must produce a copy of the original file, resampled to the appropriate size, depending on the aspect ratio of the image, and saved as a jpg. All image editing software packages will have options to perform this conversion – instructions for some common packages are included below.

3. Our projector assumes that images are in the sRGB colour space. Ideally, if you use a different colour space for working, such as AdobeRGB, your images will project closer to your expectations if you convert them to sRGB during the resampling process. Do not worry if you don’t understand colour management – most images will not be affected significantly by this, so ignore it if you’re not sure. The PhotoEntry site will confirm if you have used the correct colour space and can convert it to sRGB is required.

4. Images must be submitted for all competitions by midnight on the Sunday prior to the competition to allow time for the files to be processed, and the running order generated.

Resampling Instructions

Resampling involves generating a new file with less pixels than your original image – please make sure you do not resample the original or you will lose pixels for good. This procedure should be performed on a file copy. Below are instructions for Photoshop, Photoshop Elements, and the free program Picasa.

Note that the latter two programs have only a single field to enter the resize dimensions, and this can mean that for a landscape image, although it may be 1600 pixels wide, it can still be more than 1200 pixels high. You cannot tell this from the app, so we recommend (for Windows users) to use another free and well-established program called IrfanView.  You can download it from here. Instructions below.


  1. Open the image in Photoshop and flatten any layers (Layer > Flatten Image)
  2. Use File > Automate > Fit Image and type in the required maximum size of the image (1600 x 1200 in our case)
  3. If the image is not in sRGB, use Edit > Convert to Profile, set Destination Space to  sRGB IEC61966-2.1,  set Intent to Perceptual, and click OK
  4. Use File > Save As to save the image with a file name in the format described above, in JPEG format with high quality (10 or greater). Ensure that the check box next to ICC Profile is ticked. (It should be showing sRGB). If you are not given the option of saving as a JPEG check that your image is ‘8 Bit’ – Image > Mode > 8 Bit.



  1. Open the image in IrfanView
  2. Choose Image>Resize/Resample from the menu.
  3. Make sure that the Preserve Aspect Ratio box is checked
  4. Now if you enter 1600 in the Width box the Height will adjust accordingly.
  5. If Height is now greater than 1200, then enter 1200 in the Height box and the Width will adjust accordingly.
  6. However you do it, ensuire that Widht is not over 1600 and Height is not over 1200
  7. Click OK and then choose File>Save As to save your resample image

Photoshop Elements

  1. Open the image in Photoshop Elements and flatten any layers
  2. Use Image > Resize > Image Size and ensure that the Resize (Bicubic) and Constrain Proportions boxes are ticked, then under Pixel Dimensions type 1600 into the width box if it is a landscape format image (wider than it is high), OR enter 1200 into the height box for a portrait format image (higher than it is wide). The other number will adjust accordingly. Click OK to complete the process.
  3. You cannot convert the image profile in Photoshop Elements so there is no equivalent to step 3 in the Photoshop instructions.
  4. Use File > Save As to save the image with a file name in the form described above, in JPEG format with high quality (10 or greater).


Picasea Export

  1. Select the image(s) you want to submit in the Picasa file browser
  2. Choose File > Export Picture to Folder.
  3. Specify a folder to copy the image to
  4. Check the Resize option, and for a landscape format image (i.e. wider than it is high) enter 1600 in the size field. For an image in portrait format (higher than it is wide) enter 1200.
  5. Set the Image Quality to Custom – 95, and click Export.
  6. Open Explorer and rename the files you have just created, as per the specification.