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Printing for competition

I thought I’d share some traps I fell into when I first started sending images out for printing.

The top hint is;  The printer does not care about your FRAME size, they just care about the PAPER size. Let's break this down.  A3 paper is 297 x 420 mm.  A common A3 window in a print frame is 280 x 400mm.  So I carefully cropped and resized my image to 280 x 400mm and sent it off to the printer.  Back came the print 297 x 420mm with some of the edge of my picture clipped off behind the frame and a sliver cropped off entirely!

In hindsight, this is not the printers fault.  They don’t know if your image is A3 edge-to-edge, A3 mounted, Square or Letterbox (all possible in a standard A3 frame).  YOU have to set up whatever you need and the printer just prints it.  Let’s take a nice simple A3 window;  You set the size of your image to 297x420 then you position the picture (280x400 in this example) where you want it inside the edges of the total image (think; paper size). If you are printing square a common size is 280 x 280mm.  Letterbox is frequently 140 x 400mm (and you can save money by putting two on one A3 sheet of paper!)

How to do this?  Much easier to show than describe but I create and save an image in the frame size I want.  I then create a new blank white canvas at A3 size.  When I drag and drop the frame size into the A3 size it looks like the below image.  I’m sure Derek can show us one evening.  I have dropped some standard aperature sizes in Photoshop format under the "External" menu.

Edit;  Derek has created a "How to" here.

Of course, you can buy larger aperture sizes - 410 x 290 is common. In this case simply print a full A3 page WITH NO BORDERS.  You will lose about 5mm around the edges of your image but there will be no border to see.

One final point; both the front piece with the aperture and the backing sheet have "sides", and some apertures have a top and bottom. Take care to have everything the right way around BEFORE you stick it all down!!

Knowledge Image 1

The inside measurements are the image size, the outside measurements are the paper size. YOU must manage this otherwise the print you get back will not fit the aperture in your mount.

If you need a chart of the various sizes here’s one but usually A4 and A3 are all we need to worry about.

Knowledge Image 2

The next thing to worry about is the murky world of PPI and DPI.  The same thing right?  Well, no. PPI describes the resolution in pixels (loosely the quality) of a digital image whereas DPI describes the amount of ink dots on a printed image. Though PPI largely refers to the screen display, it also affects the print size of your photograph and thus the quality of the output. DPI, on the other hand, has nothing to do with anything digital and primarily concerns print.

Also do not get confused between Mps (Megapixels) and Mbs (Megabytes).  Mps are the number of pixels across your image (or sensor) times the number of vertical pixels.  Mbs are how much space that image takes up in your memory, and is different for every image type (TIFF, JPG, RAW etc.).

In all the camera clubs we ask you to send in images Landscape 1600x???, or Portrait ?? X 1200. These are pixel measurements. 

This is partly to level the playing field (everybody in every club uses the same resolution), partly to reduce file size and partly because screens display at 72ppi so any more is wasted.  It also helps when we post to the web because should anybody be able to steal your image at 72ppi that will produce rubbish prints.  See this article if you don't know how to do this.

When sending images for printing DO NOT reduce the pixels to 1600 or 1200. Use the maximum you have cropped to the relevant size. My recommendation would be to do any post processing-work (those that do) at the full resolution of your camera and save your images in the program native format (e.g. Photoshop = PDF files) at least 300ppi until you have finished all editing (JPG’s reduce quality each time you edit them). 

There is no standard print dot size or shape, so higher DPI does not always equate to a higher quality print, but sending images at 300ppi or slightly better will usually get good prints. You will be sending large file sizes.  

Check the printers for the file format preferred.  Use TIFF if available but DSCcolourlabs want the files in JPG format.  In this case, use the maximum JPG quality at 300ppi.

Derek has created a "How to use DS Labs" here

Knowledge Image 3

Colour space.  When saving the final print file you must ensure the file is sRGB and not RGB. This is usually the default but to check in Photoshop; With your file open, simply go to Edit > Convert to Profile. A window will pop up displaying the ‘source space’ (which is the current colour profile) and the destination space is what you would like to convert to. Find ‘sRGB IEC61966-2.1’ in the drop-down and then click OK. 

Probably best to do this as step one in your editing as colours may change slightly. Most applications allow you to choose the colourspace and DSCcolourlabs only accept sRGB files.  (This is common for many external printers.)

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