Photoshop

2.1 - Modifying an existing bitmap image

To modify an existing bitmap-based file (e.g. tif, gif, jpg, bmp) so that it is RSC-compatible, perform the following steps:

1. From the "File" menu select "Open". Select the file you wish to modify, then click "Open".
2. Remove any unwanted white space from around the image using the "Crop" tool. Consult "PhotoShop Help" if you need more details on how to do this.
3. From the "Image" menu select "Image Size...". A window similar to the one below will appear. Make sure the "Resample Image" tick box is not ticked, then set the "Resolution" to "600 pixels/inch". The "Width" and "Height" boxes now show the size of the current image at 600 dpi (the resolution required by the RSC). Make a note of these values and then click "OK".
   
   

   

   
   
4. Examine your image. Remember, your final illustration should fit within and make good use of a column width of 8.3 cm (or 17.1 cm if double column width).
   
   
   • If the image is too small, the only way to improve it is to go back to the program that originally created it and obtain a larger or higher resolution version.
   • If the image is the correct size, proceed to point 6 below.
   • If the image is too large, PhotoShop can attempt to reduce it to the correct size. Proceed to point 5 below.                 
   
   
5. To reduce the size of an image while maintaining the resolution means using fewer, larger squares to make up the image. This involves averaging the colour of adjacent smaller squares to produce larger ones. This works best if (i) the image mode supports lots of shades, and (ii) the image is scaled by sensible values to make the averaging process easy. Thus, to reduce an image in size while minimizing quality loss, do the following: 
   
   
   • From the "Image" menu, "hover" the pointer over the menu item "Mode". A sub-menu will appear. If your image is black and white, select "Grayscale"; if it is in colour, then select either "RGB Color" or "CMYK Color". PhotoShop may ask for more information before converting - accept the default settings offered.
   • From the "Image" menu select "Image Size..." (as in step 3). Make sure the "Resample Image" tick box is not ticked, then set the "Resolution" according to this table: 
     
        Reduce to 75% = 800 pixels/inch
        Reduce to 66% = 900 pixels/inch
        Reduce to 50% = 1200 pixels/inch
        Reduce to 33% = 1800 pixels/inch
        Reduce to 25% = 2400 pixels/inch
     
     Now place a tick in the "Resample Image" box, and set the resolution to 600 again. Click "OK".                
   
   
6. From the "Image" menu select "Canvas Size...". A window similar to the one below will appear. Set the "Width" to "8.3 cm" (or "17.1 cm" for double column width) and the "Height" to "23.3 cm". Click "OK".