I've been asked how to re-size images thousands of times before (I worked as a graphic designer for 15+ years). I was asked this very question last night by a member so thought I'd throw together a quick how to for anyone that's interested.
The first step by step is using a free online image editing tool called Pixlr. It's quick simple very powerful and best of all it's Free. I used this generic editor because everyone has access to it and I don't have to worry about which version of a particular program you are using. The person asking for help is using photoshop so I included a PS tutorial. The photoshop tutorial was done in CS5 design premium so depending on which version you have installed may look a little different.
Before we start:
Its a good idea if you have the hard disk space, to have at least three folders, one for Originals (straight off the camera) the other for Print and for Web. Always transfer images off the camera to the originals folder, Never work on them. If you're creating an image for the forum, copy that particular image out of Originals into the Web folder. We'll be working with this file, if anything goes wrong, there's no need to break out in sweat as you have all you untouched files stored in Originals, right?
Editing images using Pixlr
Go to the online editor ; http://pixlr.com/editor/
Open your file/s
1. Select the crop tool from the tool bar on the left of your window.
2. You will notice a tool preferences/settings panel above the tool bar and underneath the black menu bar. You have three options of constraint (view the exploded diag). No restriction, Aspect ratio and Output size.
3. I used aspect ratio maintaining a classic 4 to 3 ratio as in a standard 35mm photo. You could specify an output size for example 800px X 600px and kill two birds with one stone by eliminating step 7.
4. Click and hold down the left mouse button on the image, then drag a marquee/box from the top left to the bottom right of the image portion you want to show. You are trying to frame/crop the image here, don't worry if you haven’t achieved this with the marquee/box displayed. You can move the crop marquee/box by clicking and holding the left mouse button anywhere inside the marquee and repositioning it. You can also resize the marquee by clicking on any of the four corners and dragging them in or out.
5. Once you're happy with the crop double click (click twice) anywhere inside the marquee to apply the crop. Or alternately simply press enter/return on your keyboard.
6. Go to the Image menu, select image size. This will bring up the image size dialogue box, refer to no. 2 on the diagram.
7. Make sure the constrain proportions box is checked. This next bit is crucial to not lose image quality. The size displayed in pixels is the actual image size. Make sure that the number is higher than what you intend to re-size it to. In this example the original image is 1950px X 1463px and we are re-sizing/downsampling the file to be 800px wide. Type 800 in the width dialogue box, the height is automatically adjusted to maintain the image proportions. Click OK to apply and accept the changes.
8. This step is optional, after re-sizing the pic you can sharpen the image before saving it. Don't go overboard on the sharpening, it's not pretty. Use the settings in the diagram of the Unsharp mask dialogue as a guide. Set the radius and threshold to the numbers in my example and depending on the image in question change the amount from between 30-55 but no more. If you need to go higher your image wasn't sharp to begin with.
9. Save your image, you're done.
Editing images using Photoshop
Ok, now for for the photoshop version, I'll try to condense this taking into consideration that you've read the Pixlr version first.
1. Select the crop tool, you can define a size as I did in this example 800px X 600px.
2. Drag a crop marquee/box around the portion of the image you want to show. Double click on the marquee or press enter/return on your keyboard to apply the crop.
3. The second diagram shows some options I like to use when cropping an image. The rule of thirds and a shield colour makes life easier, depending on the image. The default is also fine.
4. An alternate option is to leave the crop size setting parameters blank. This allows you to crop the image to whichever shape you desire. If you go down this road you will have to re-size the image separately.
5. After step 4 bring up the image size dialogue box. Check Constrain proportions, change the width of the image to the pixel width you want the file to be. In this example I've used 800px refer to the steps in the diagram it should be self explanatory.
If you have any questions or queries, please don't hesitate to ask.
The last image I have included shows one of my flies with two levels of sharpening. The left image is the unsharpened image, the middle image is at the level of sharpening I've chosen and the third is to show what going too far looks like (Don't do it).
Cheers
Karsten
