I think we’ve all been irritated by someone emailing us large images – files that are way too big for their intended use. This ignorance regularly cause our mailboxes to become full and resulting in all incoming emails to be rejected.
It’s amazing to see how many “computer literate” users don’t have a basic understanding of resolution. Maybe it is because people don’t know where to find the necessary info or because they think it’s too complicated? Like knowing how to draw up a budget or where the things that we consume come from I also believe that knowledge of basic digital concepts is something that every computer user should develop.
Below are some basic guidelines that we cover in our Beginners Course in Photography. Hopefully some of you would find this info useful and help to demyth some basic digital concepts related to photography. Feedback or questions are welcome.
BASIC DIGITAL GUIDELINES
- A digital photo is a two dimensional image made up of red, blue and green pixels.
- The size of a photo consists of the amount of pixels which is calculated by multiplying the amount of pixels on the X and Y axis. Ie a photo on a computer screen could be 600 x 800 pixels.
- Resolution (dpi = dots per inch) refers to the density (how close the pixels are to each other.
- The image appication (ie computer screen, newspaper or magazine) have different resolution (dpi) requirement. This means that three different photo’s with the exact same physical size will differ in file-size. Ie a 15 x 22cm photo published in a newspaper, a website and a magazine.
|A. Website||Size||B. Newspaper||Size||C. Magazine||Size|
|15x22cm @ 72dpi jpeg||800k||15x22cm @ 175dpi jpeg||4.59MB||15x22cm @ 300dpi jpeg||13.5 MB|
Note that the jpegs in the sample above are not compressed .
5. A photo on a computer screen with a higher resolution than necessary will not display any better as a photo where optimal resolution is used. (in other words a bigger photo is not always better and is a waste of time and space!).
6. It is not possible to add pixels to a photo to increase the resolution of a photo (in above mentioned example: from A to C ). That is why it is important to rather save the original file as back-up and use a copy for editing.
7. Most higher end cameras have the option of capturing RAW image files. Raw image files are sometimes called digital negatives, as they fulfill the same role as negatives in film photography: that is, the negative is not directly usable as an image, but has all of the information needed to create an image. Like a photographic negative, a raw digital image may have a wider dynamic range or color gamut than the eventual final image format, and it preserves most of the information of the captured image. The purpose of raw image formats is to save, with minimum loss of information, data obtained from the sensor, and the conditions surrounding the capturing of the image (the metadata).
8. Jpeg files are most commonly used in photography. For each time it is opened and saved there is a destructive form of compression happening – this means that every time a JPEG file is opened and resaved data is discarded leading to a decrease in image quality.
The folder naming method above is a good way of saving your digital files and could save you many hours if used diligently. Printing an index with thumbnails of your files will also help you to quickly find your images.