By Harry O'Connor

Continued from Part 1

4. Size Matters

Even though it may sound a little technical, it is very important to try and understand the basics of image sizes early on when learning Adobe Photoshop. To see image size properties go to Image>image Size. You should be able to see:

Pixel Dimensions and Document Size.

As a general rule work intended for print based output should have the width and height (Document Size) as it is to be printed and the resolution should be 300dpi (Dots per inch, or as Photoshop calls it ‘pixels/Inch’). Increasing any of these factors will increase the file size exponentially, but will not substantially increase image quality. Similarly reducing these factors will reduce the file size and image quality. I have had many discussions with many people about image size (how sad am I?) and I have come to the conclusion that the most important fact with image size is not the dpi, or the width in inches or centimetres, but the file size.

For an A4 image intended for print the file size should be around 24 megabytes. Screen based work such as web design is normal outputted at 72dpi. I believe the best way to get image sizes right for things like the web and multimedia projects is to view the image as it would appear onscreen.

To do this simply choose View>Actual Pixels.

Now you can see if the image is too big or small. If you know the exact width the image should be you can type this into the image size properties. Generally screen based images do not need to be bigger than 1024x768 pixels as this is the size of the average monitor in pixels.

5. Understand what you are saving

Hopefully there are still few people that will have read this far and won’t be completely scared off by all that technical talk above! Anyway, as with all programs Photoshop has the ability to save your work as you produce it (duh!). However, unlike most other programs, with Photoshop there are a host of different formats in which you can save as. I have listed a few of the most commonly used below:

.psd - Photoshop Document.
This is what you should save as if you intend to work on the file again. This format saves everything from fonts to layers, however remember that not everyone has Photoshop, so if you wish to distribute your image you should consider another format.

.tif - TIFF file.
This is the most commonly used format for bitmap based (pixel based) artwork. It does not loose quality, but you can compress TIFF files to reduce the file size if you wish.

.jpg - JPEG
Introduced by a group of photographers and journalists as a standard way of distributing compressed files, this format is great for the internet and emailing work. With JPEG’s you can choose the quality vs. file size ratio when you save. I normally save my jpegs at 60-70% quality. JPEGS make big images into tiny file sizes.

.gif - GIF.
GIF’s are another way of reducing file sizes but work best with images that have few colours such as a 3 colour logo for a website. If you are saving a photographic image and want to keep the file size down you should use JPEG.

Above are just some basics to get you started using this useful program. As I said earlier, the best way to learn about it is to practise and have fun. Should anyone need any specific help with Photoshop, they can email me at harry@voodoochilli.net . Please do not send files to me, simply outline your problem and I will see if I can help.