Preparing a Digital Image File for Projection

ASPECT RATIO (AR)

This is the boring bit.   AR is the relationship between the width and height of an image.   Most projectors use an AR of 4 : 3 (eg 1400 by 1050 pixels), though the KCC projector is also capable of projecting video images at an AR of 16 : 9.    Images from compact cameras generally have an AR of   4 : 3 which means they fit exactly.    But digital SLRs produce images with a 3 : 2 AR (the same as film) so that the image either has to be cropped (Option 1) or framed (Option 2) to fit a digital screen.   There is more on Options 1 and 2 below.

HOW TO MAKE YOUR DIGITAL IMAGE PROJECTOR FRIENDLY

STEP 1 - CONVERSION TO 8-BIT

With your image open in Photoshop go to IMAGE  > MODE and, if necessary, drop down to 8-bits per channel which you click on.   [If you have been using a RAW file or 16-bit sized file this will enable you to convert the image to a JPEG file in Step 4.]

STEP 2 - CONVERT TO PROFILE  

Repeat IMAGE > MODE and then go down to CONVERT TO PROFILE.

My screen then shows the box above. If the Source Space is already sRGB, don’t do anything except click Cancel.   If the Source Space is not sRGB, then go the DESTINATION SPACE and change the PROFILE to sRGB IEC61966-2.1 and, if necessary, set ENGINE to Adobe (ACE) and INTENT to Relative Calorimetric.  When done click on OK.  Digital projectors use the sRGB mode – which has a smaller gamut.  [If you use Adobe RGB 1998, which has a wider gamut of colour, some of your colours may change very slightly.]

STEP 3 - SIZING OR RE-SIZING YOUR IMAGE: 

Compact camera users should go to IMAGE > IMAGE SIZE and in the dialogue box check that the PIXEL DIMENTIONS are 1400 pixels for the WIDTH and 1050 pixels for the HEIGHT.    If not, make sure that the CONSTRAIN PROPORTIONS and RESAMPLE IMAGE  boxes are ticked and then change either the WIDTH or HEIGHT to the required number of pixels.   Remember that 1400 and 1050 pixels are maximum sizes.    However, if you have an image in PORTRAIT format you may wish to use the method described in Option 2 below to avoid having a blank space on  either side of the image. See example below: 

Digital SLR users have more work to do to adjust their images to fit the screen shape.   I use Photoshop CS3 but believe the processes will be similar for earlier versions of Photoshop and in Elements.   There are two ways of fitting an image to the screen shape:

            Option 1.         This uses the CROP TOOL to re-size the image.    Open the image (use FIT ON SCREEN if necessary) and select the CROP TOOL.   In the tool options bar at the top of the screen set the WIDTH to 1400 pixels and the height to 1050 pixels.    Move the pointer into the image and drag it diagonally from the upper left to the lower right corner of the picture.     This will create a rectangle (marquee) of exactly 1400 by 1050 pixels.   This can be dragged over the image by positioning the pointer anywhere inside the marquee.    When the marquee is in the right place, press the RETURN key to crop the image 

            Option 2.         Particularly suitable for images in portrait format or where it is important to keep the shape of an image that was perhaps taken with an Aspect Ratio other than 4 : 3.   This will use layers and a new background document to frame the image.    I will use a portrait image as an example.    To begin with, open the image and in IMAGE > IMAGE SIZE make the HEIGHT 1050 pixels.    With the CONSTRAIN PROPORTIONS and RESAMPLE IMAGE boxes ticked, press OK and allow the width to take care of itself (it won’t be more than 1400 pixels). 

            You now have an image 1050 pixels high but less than 1400 pixels wide.   There are two easy ways of filling out the image with colour, to 1400 pixels, to fit the screen shape:

                        One is to go to IMAGE > CANVAS SIZE and in the dialogue box set a width of 1400 pixels and a height of 1050 pixels.  Ensure  the box marked RELATIVE is unchecked and that the anchor point is central.   Next, set the CANVAS EXTENSION COLOUR to Black (the colour most clubs use) and click OK.   

Alternatively, with the image on-screen, go to FILE > NEW and create a new document of size 1400 by 1050 pixels.    Set the resolution to the same dpi or pixels/inch as the image itself.   Leave everything else as it appears and press OK.  

 

Next go to EDIT > FILL, select a COLOUR (most clubs use black) and click OK.  

Now go to the LAYERS PALETTE and click on the layer with the file containing your image (probably labelled BACKGROUND) and drag the file (not the image itself)  into the new black (UNTITLED) document whilst holding down the SHIFT key.    (Holding down the SHIFT key will ensure that the image is positioned centrally in the black space).   If required, you can re-position your image using the MOVE tool.

When satisfied, go to LAYER > FLATTEN IMAGE.

STEP 4 - NAMING AND SAVING THE IMAGE AS A JPEG

For the file name type in the title of your image followed by an underscore (no spaces) and finally your name (eg Angel_Ann Smith)

Photoshop and Elements have an easy way to save an image as a JPEG.   Go to FILE > SAVE AS and click on SAVE FOR WEB.   A new window opens.    Set the file type to JPEG (it’s usually the default); set quality to 100; check OPTIMIZE; uncheck PROGRESSIVE; uncheck ICC PROFILE and click SAVE. 

 

Alternatively (especially for earlier versions of Photoshop or Elements) go to FILE > SAVE AS.   In the SAVE IN dialogue box enter the destination drive or folder; the file name (see above) and in the box FORMAT choose JPEG.    Click SAVE and in the JPEG OPTIONS dialogue box select the maximum quality for JPEG and in FORMAT OPTIONS select Baseline (“Standard”), then click OK.

This guidance has been prepared by Brian Freeman and Ann Smith, to the best of their ability and mindful of the fact that, with Photoshop, there is always more than one way of achieving the desired outcome.

20/01/09