Adobe Photoshop 7 Tutorials
Vector Tools / Raster vs. Vector
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Subtitles of the Movie (Adobe Photoshop 7 / Vector Tools / Raster vs. Vector)
Well what is the different between a raster type of image versus a vector type of image? Photoshop works quite well with both raster and vector, but it started out being essentially a raster image editing application. Raster image type of editing is based on a pixel-based image, and of course we know that any image of course is actually a grid of pixels. And if we zoom in, you can see the actual pixels in this image. So there is a collection of pixels on a grid, and any pixel can have in my RGB document, one of about 16-million colors. And if they have a smooth transition, you can create a continuous tone type of image. Very much of what we expect from a photographic type of image. Well there is another type of graphic technology called vector imaging. And vector imaging is based paths, which create very sharp outlined graphics. Applications such as Adobe Illustrator specialize in vector graphics. Photoshop has the ability to mix and match vector graphics with raster graphics, and just a couple of different features of that would be something such as generating type in Photoshop is based on vector graphics, as well as some of our shape options also generate vector graphics creating very sharp-edged solid colored shapes. And we can also create paths using the pen tool to create a precise outline around an object such as this apple, and then convert that path into a selection to create very precise selections. Well, to show you one of the features and benefits of vector graphics, I have added this cow to my document here called the raster cow. And I want to show you what happens when we enlarge this cow several 100%. So with my cow selected, and you know that this is a pixel based raster type of cow, I'm going to choose free transform. And I'm going to hold down the shift key, and just drag this up several 100% probably 400%. And of course at this point, Photoshop is giving me a low-resolution proxy of what the final rasterized image will look like. So when I commit to this size change, Photoshop will interpolate up or res up this cow. And what it's going to do is it adds pixels in order to make this cow as good as can in its new size. And there is my new enlarged cow and notice what happened. Well, since the cow didn't have a lot of pixels to start with, Photoshop did the best job it could to make the cow look good, but frankly it looks terrible. It looks very soft and fuzzy. And of course this is one of the problems with working with raster images that might be too low resolution when you try to go edit them, and res them up. Well, here is a different type of object. This is a vector-based shape, and if I click on it you can actually see that path that creates the shape. Go ahead and use my zoom tool and zoom-in, drag zoom to my vector-based shape. Now it looks like there are pixels in this vector-based shape, and in fact there are, because this vector-based shape is living in a raster image application. So your vector-based sharp-edged shape is of course limited to the resolution of your actual document. However if you save out in certain file formats, any vector based information will be printed using your printer's resolution. Which is very often much higher than the document resolution. And the net effect of that is it creates a very sharp-edged vector graphics, maintaining sharp-edged logos and text. And as I mentioned earlier, vector graphics of course are based on paths, and you can see if we can use one of our path selection tools or direct selection tool, you can actually click on this shape and edit the paths and make up this sharp-edged shape. Well, I'm going to copy this vector graphic, and I'm going to convert this particular one into pixels - I'm going to rasterize it. So it is fixed in the world of pixels, and loses its sharp-outlined vector-based information. Layer menu>rasterize>shape will convert it into pixels. And now I have one that is vector, I'm going to hide the cow, and one that is raster. Well, here's my rasterized shape. And I'll go ahead and I'll do the same thing, I'll res it up so that's command + t. And I'm just going to increase its size, and I'll commit to that. And very similar to the cow, you can see how soft and fuzzy my shape got. Well, I'll go up to the vector version of this shape. And do the same thing command + 'T' to bring up free transform, and I'll res this up or increase the size to about the same size as the one underneath. Commit to that and now notice how sharp-edged the vector version of my shape is. So, if you are working with graphics that can be maintained as a solid color, because that's one of the limitations of vector graphics. If you are working with that type of a graphic, I recommend working in the world of vector paths and shapes, as opposed to converting it or rasterizing your shape. Of course one of the nice things of working in the world of raster and pixels, is that of course we could create a custom colorized effect - painting different areas of this different colors, which a vector graphic would not support. So there are times when you want to use vector graphics, such as type and sharp-edged logos and paths, and there are times that you will be using raster type of graphics, which of course is the overall emphasis of Adobe Photoshop.
Tutorial Information
| Course: | Adobe Photoshop 7 |
| Author: | Andrew J. Hathaway |
| SKU: | 33329 |
| ISBN: | 1889347272 |
| Release Date: | 2002-09-05 |
| Duration: | 11 hrs / 152 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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