| In today's world it is important to understand image | | | | be landscape rather than portrait. |
| resolution and size, the basics are fairly easy to get to | | | | How does Resolution affect File Size? The more |
| grips with but the intricacies can be incredibly complex. | | | | pixels an image contains the larger the file is likely to |
| The article this week has been inspired by many of | | | | be; this is due to the fact that storing information |
| our customers. On a weekly basis I get asked the | | | | relating to 10 million pixels is liable to require more |
| same question 'how many pictures will I be able to fit | | | | space than saving a lower resolution 1 million pixel |
| on this' when talking about the size of a memory card | | | | image. |
| or USB flash drive. I thought it was about time to | | | | There are several other very important factors to |
| spread the word. | | | | consider: |
| What is Image Resolution? A pixel is a unit of | | | | File Format - Over the years there have been many |
| programmable colour on a computers display and by | | | | different image file formats, each introducing new |
| combining many of them together we are able to | | | | advantages and disadvantages and covering them all |
| create an image; by increasing the number of pixels, | | | | would take an article in itself. The two you are most |
| the resolution is also increased. Basically resolution | | | | likely to come in to contact with when using a digital |
| refers to the number of pixels used. On the whole, the | | | | camera are JPEG (smaller images that often include |
| quality of the image will increase with a greater | | | | compression) or RAW (Completely unprocessed |
| number of pixels as we are able to store a greater | | | | images files which are of a higher image quality but |
| amount of detail. | | | | also substantially larger) |
| How is Resolution Measured? Resolutions are | | | | Colour Depth - Along with the total number of pixels |
| generally expressed in two different formats - either | | | | that constitute an image, we also have to consider the |
| the total number of pixels used in the creation of the | | | | potential number of colours each pixel could be. If, for |
| image are given or the pixel dimensions of the image | | | | example you save your image as a 'line art' image |
| are given. | | | | where each pixel can be either black or white then the |
| Most digital cameras express their maximum resolution | | | | amount of data required to store this information is |
| in terms of megapixels (millions of pixels) that can be | | | | less than if you set a colour depth of 'true colour' |
| used to create an image; an 8 mega pixel camera | | | | where each pixel could be one of 16,777,216 potential |
| would be able to break a picture down in to 8 million | | | | colours. |
| pixels hence giving a higher resolution that a 5 mega | | | | Compression - Many image formats, such as JPEG |
| pixel camera. | | | | allow you to adjust the amount of compression that is |
| The resolution of a computer image on the other hand | | | | utilised when saving the image. Compression can work |
| is usually expressed by giving the number of pixels | | | | in a number of different ways but ultimately it works to |
| present on a line and the number of lines used in the | | | | minimise the amount of data required to save the |
| image. For example, an image measuring 1600 x 1200 | | | | image. This is usually achieved by looking for areas of |
| would contain 1600 pixels per line and a total of 1200 | | | | commonality (for example a shape or pattern) and |
| lines giving a total of 1,920,000 pixels (1.92 mega pixels). | | | | saving the description of that area which the computer |
| As the image contains a greater number of horizontal | | | | can then later reproduce when reloading the image |
| than vertical pixels we can assume this picture would | | | | rather than defining each individual pixel. |