I understand that for print quality an image of at least 300dpi is normally required. On this basis a 7” x 5” picture would require 2100 x 1500 dpi, which is over three million in total. This suggests a three million-pixel camera might struggle to do the job, but I have been surprised that people say that it is even possible to get quality A4 prints from a three megapixel camera. Can you explain why this is so, please? E. Bowman
You are right to say that a print made from a digital file needs a certain number of pixels but a good three million-pixel file can be made bigger using software that employs a process that we call INTERPOLATION. This uses complex mathematical algorithms to invent extra information in between the pixels recorded by the camera.
There are a number of factors that directly affect the suitability of an individual file for enlargement. These include: