This note gives guidelines for the preparation of digital images intended for projection on the Canon XEED SX50 digital projector which is now available for presentations and slideshows. It is hoped that it will also be used for competitions in the near future. The guidelines may be modified in the light of experience; comments are welcome. Please ask for help if any aspect of this note is unclear.

IMAGE SOURCE:

Digital images for projection may come from any suitable source. The main ones are: digital camera, scanned film (slide or negative), and scanned print. Images may or may not have been adjusted in an image editing program such as Photoshop.

IMAGE FORMAT:

 The ideal image format is a width-to-height ratio of 4:3 since this format will completely fill the screen. Any format may be used however - there is no need to crop the image to this ratio, although you can if you wish. Many digital cameras have a 4:3 format but many digital SLR cameras do not, and neither do film cameras. If the format is not 4:3, the projector fills the unused screen area with black. In particular, portrait (upright) format images will be projected with a large back area on either side.

IMAGE ADJUSTMENT:

Start by making a copy of your image to work on, so that your original is protected. Before altering the image size, make any other adjustments required, (eg cropping, colour balance etc). Flatten the if it contains more than a single layer. If you plan to carry out sharpening, do not do it yet.

IMAGE SIZE:

 The projector has a maximum resolution of 1400 x 1050 pixels, and this is the "ideal" image size for projection. The laptop computer used to drive the projector has the same resolution. The image does not have to be this size however. If the image is too large or too small, it will be automatically adjusted by the software to fit the projector, but this is a process over which you have no control, and so it is better to re-size the image yourself. It is inadvisable for both the width and height to be less than ideal as this will lead to loss of sharpness. If the image is larger than ideal, the file size will be bigger than it needs to be and it may take longer to load.

If you wish to adjust the image size in Photoshop, first make a duplicate of the image (if you have not already done so,) or save it under a different name to avoid overwriting the original. Next, select Image > Image Size... from the menu. This opens the dialog box shown below as it might appear for an image of ideal (4:3) proportions.

THE FOLLOWING NOTES APPLY TO USE OF THE ST ANDREWS PHOTOGRAPHIC SOCIETY PROJECTOR,

For internal competitions please refer to these notes.

For digital projection on other projectors or in external competitions please refer to the organisers of the event.

Initially, the width and height will be different from those shown. Make sure that "Constrain Proportions" and "Resample Image" are ticked, and that "Bicubic" is selected as the resampling method. Also make sure that the units are pixels in the upper (Pixel Dimensions) part of the dialog box. For a landscape format image, set the width to 1400 pixels. The height changes automatically. If the resulting height is more than 1050, set it to exactly 1050. The width will decrease. For portrait format, set the height to 1050 pixels. Do not try to set both width and height as they are linked. Ignore the "Document Size" section, including "Resolution", as this is irrelevant for projection. Click OK. Save, making sure that you do not overwrite your original. Note that the above example is based on Photoshop 7; details may be slightly different in other versions.

To summarise, a 4:3 image should have a width and height of exactly 1400 and 1050 pixels. A landscape image (more than 4:3) should have a width of 1400 pixels. A portrait image, or a landscape one of less than 4:3, should have a height of 1050 pixels.

SHARPENING

If you wish to sharpen the image, this is likely to be more effective if done after the image has been set to the final size. Take care not to over sharpen as this can give an unpleasant appearance.

COLOUR MANAGEMENT

The image viewing software used at present does not use colour management, unlike Photoshop which uses colour profiles to calibrate the colours. Consequently, a projected image may look different from how it appeared in Photoshop. If the image has the "sRGB" embedded profile, there should be no problem, as the projector will be used in its sRGB mode. Most digital cameras automatically put this profile into JPG format images. For images with a different profile, or no profile, it is recommended that they should be converted to sRGB. To do this, select Image > Mode > Convert to Profile... and then select sRGB as the Destination Space. (Example from Photoshop 7). There should be no change in the appearance of the colours in Photoshop, and the colours should still be correct when projected. This does not guarantee correct projected colours as there are other reasons for colours being wrong. If your projected images do not look as expected, please discuss this with a committee member.

SAVING:

After all adjustments have been made, save the final version and do not make any more changes to it. In principle, any of the usual image file formats can be accepted, (eg, TIF, PSD, JPG), but to ensure maximum compatibility with a variety of software, it is best to use JPG format, with a high quality setting. Make sure that the sRGB profile is included when saving.

MEDIA:

Image files can be accepted on any of the following media: CD, DVD, USB Flashdrive, camera memory cards or floppy disc, with CD being the preferred option. Whatever you use, make sure that your name is on it. On certain occasions, files containing complete slideshows can also be accepted, although not for competitions. Suitable slideshow files can be created with various programs including Powerpoint, Irfanview, PicturesToExe, ProShow Gold, Photoshop Elements, and Lightroom.

SUBMISSION:

For competitions, the submission date for entries will be announced. For other activities such as informal showing of members' images, please bring them one week in advance if possible.

Notes prepared by Alaistair Ramsay, January 2008.