Files formats & how to resize images
Image Resizing is very important, whether taken from your digital camera or a scanner, they are far too large to send over the internet. These original files take forever to download, if they ever do that is, especially on a dial-up connection. Many digital cameras produce JPEG files of about 2MB (megabytes), that's 2,000KB, which is thirty to forty times to large, that shows you how important resizing images is. These problems arise most often when you send images as email attachments, add them to web pages or upload them to facebook, eBay or similar. You might be keen to share your photos of the weekend, a party, a night out at the casino or night club with your friends but most photo sharing web sites, would not accept files above a certain size. It is essential to resize original images before using them for any of these tasks. The tutorial below will help you understand the procedures required for images used for web pages, which are also ideal for sending as email attachments.
File formats
For Print
Image resolution is the most important factor, when preparing for print. For high-colour-depth images, TIFF is a popular format along with JPEG, and PNG (Portable Network Graphics). PNG was created to improve upon GIF, and can have transparency. Tiff (Tagged Image File Format) which is abrieviated to TIF, are the most common in commercial printing. High Quality JPEG (Joint Photographic Experts Group) abrieviated to JPG, is very good also, but when used for the web needs to be compressed or it would be to large an image, therefore take to long to download.
For the web
The most common image file formats for the web are JPEG and GIF (Graphics Interchange Format), although I personally prefer, PNG (Portable Network Graphics) to GIF in most cases, as they are far superior, but they often come out as a larger file and are not supported in some browsers. JPEG's are often used for photographs and any graphic without the need for transparency, whereas a GIF and PNG is used when you require a partial or total transparent background and for animation.
Resizing an image
Here we will concentrate on how to resize an image for both print and the web. Firstly you will need to work out roughly what size image you require. For example if you were saving for the web, lets take the image of my art ebook on my home page. This was originally 10 inches square, as I had a professional printer, print off two copies when I first created this book. To show this on my home page I had an idea that a reasonable size would be, not more than 2 inches square. So below are the steps I took to save a copy for the web.
Step 1: Open the art work or photograph you want to resize. Then go to 'File' 'New' and in the dialogue box enter the size you require. For my settings, I chose a width & height of 150 pixels (this is roughly 2inches), resolution 72 (pixels per inch) as anything higher will increase file size and take to long to download. Make sure it is set to RGB which is for a computer screen, (CMYK is for print). Click OK. If you want to resize for print, then choose a resolution of 180 - 300 and CMYK color mode, with a size suitable for your printed page.
Step 2: With your new blank image open, activate the large image you want to make a smaller copy of. You should have something similar in the different sizes to the my images shown below, if saving for the web. Saving for print the size difference would probably be minimal in comparison.
Now click on the large image to activate it, and go to select all to get the marquee around it, then 'Edit copy', now click on the small blank image to activate it and go to 'Edit paste'. You should have something similar to the image below, showing only a small section of the huge image file. If you were resizing for print you would obviously see a larger proportion of your image.
Step 3: Now go to edit transform, then view fit on screen (or control and zero) to view the entire bounding box. See image below. If you hold SHIFT you will keep the proportions of your transformation and it will remain square.
Keep hold of the shift key and slowly reduce until you have the entire image in view. Press enter to release the tranform tool, then go to file 'Save for Web'. Remember if you are resizing for print, after releasing the transform tool, you would just click 'save as' with your higher chosen resolutionof 180 - 300, along with your higher setting.
Here is the actual resized image that is on my home page, which if printed, would be about 2" square.