Digital Images: Size, Size Type Jeanne Gleason, Ed.D. jgleasonnmsu Executive Producer Agricultural Communications

2. Size and Size What is the difference? Size � how big is it? Memory � how much space does it take to store? We talk about image �size� in two different ways. One is the size of an image� like a portrait on a wall. We might say it is 11x14 inches. The other is the how much space it takes up on the hard drive to store.We talk about image �size� in two different ways. One is the size of an image� like a portrait on a wall. We might say it is 11x14 inches. The other is the how much space it takes up on the hard drive to store.

3. How big is it?There are lots of ways to think about size We think in this way about other items. If I were to ask you how big a letter that you wrote is; you might respond differently depending on why you thought I was asking. Photos - and all images - are the same way. There is the physical size of it� and the storage size of it.We think in this way about other items. If I were to ask you how big a letter that you wrote is; you might respond differently depending on why you thought I was asking. Photos - and all images - are the same way. There is the physical size of it� and the storage size of it.

4. How big is it?SIZE gives the dimensions The dimensions can be measured in page length, inches, words, meters� any unit of measurement. We can measure images in pixels� but more on that in just a minute.The dimensions can be measured in page length, inches, words, meters� any unit of measurement. We can measure images in pixels� but more on that in just a minute.

5. How big is it?MEMORY gives the space taken to store Just like letters and music� the larger a photo, the more size it takes to store. So� you may now be saying a HAAAA� so that is how big a photo is? A 5x7� photo is 796k? Great�. But� NO. In addition to the size in inches, a photo�s size depends one other thing: its resolution.Just like letters and music� the larger a photo, the more size it takes to store. So� you may now be saying a HAAAA� so that is how big a photo is? A 5x7� photo is 796k? Great�. But� NO. In addition to the size in inches, a photo�s size depends one other thing: its resolution.

6. ResolutionHow many pixels per inch? What is a pixel? Unit of measurement� square Make up computer monitors When printed, 1 pixel = 1 dot of ink A pixel is how we measure images on screen. You may be measuring in pixels without knowing it. When we talk about a computer monitor being 640x480 or 1124x768, we are talking in pixels. Incidentally, when we print� pixels are usually converted to dots of ink.A pixel is how we measure images on screen. You may be measuring in pixels without knowing it. When we talk about a computer monitor being 640x480 or 1124x768, we are talking in pixels. Incidentally, when we print� pixels are usually converted to dots of ink.

7. Resolution Computers usually have 72 pixels per inch (ppi). Look closely at a screen to see them. When you print at 72 ppi, you can definitely see them.

8. ResolutionThe kitchen tiles of the digital photographs A lot of people get confused by the concept of resolution� but it is just like shopping for kitchen tile. Imagine you were creating a tile mosaic in your kitchen� you wanted to figure out how many times you wanted to use? You could use larger tiles� and the image would be about 28x28 tiles� medium sized tiles with an image 54x54 tiles, or small tiles, with an image 128 x128 tiles. What do we know about the quality of the picture? With more tiles�the image is smoother and clearer. You can see more detail. The more little squares that are in an image, the better the image looks. Remember� digital photos are also made up of little squares. How many little squares in each picture? That is the resolution�A lot of people get confused by the concept of resolution� but it is just like shopping for kitchen tile. Imagine you were creating a tile mosaic in your kitchen� you wanted to figure out how many times you wanted to use? You could use larger tiles� and the image would be about 28x28 tiles� medium sized tiles with an image 54x54 tiles, or small tiles, with an image 128 x128 tiles. What do we know about the quality of the picture? With more tiles�the image is smoother and clearer. You can see more detail. The more little squares that are in an image, the better the image looks. Remember� digital photos are also made up of little squares. How many little squares in each picture? That is the resolution�

9. ResolutionHow many squares (pixels) per inch Same with photos� how many squares do you want in your image? What happens when we have more squares, or more pixels, in the image? It becomes smoother and better quality.Same with photos� how many squares do you want in your image? What happens when we have more squares, or more pixels, in the image? It becomes smoother and better quality.

10. ResolutionWhat resolution should MY images be? Of course, the more pixels you have, the larger the image. So, we have the delicate balancing act of getting as many pixels as we can, with as little memory. Generally, here is a guide for resolution. Decide what you want to do with your image, and pick your resolution accordingly. A suggestion: if you have an image that you are going to use for web, for a newsletter, and also to print and frame, you will probably want to save three separate versions of the photo � one in each resolution.Of course, the more pixels you have, the larger the image. So, we have the delicate balancing act of getting as many pixels as we can, with as little memory. Generally, here is a guide for resolution. Decide what you want to do with your image, and pick your resolution accordingly. A suggestion: if you have an image that you are going to use for web, for a newsletter, and also to print and frame, you will probably want to save three separate versions of the photo � one in each resolution.

11. ResolutionHow do I make my images the right size? Any image editing program will let you re-size your image. Here�s a simple approach. This top part tells you how many pixels are in your image� ignore that if you want. It�s like counting the tiles in your kitchen� you can but it isn�t really necessary. First, decide what resolution you want to use� here, I�m preparing this image for printing at 300 ppi. Second, Adjust the image in width and height in inches� checking to make sure the resolution stays.Any image editing program will let you re-size your image. Here�s a simple approach. This top part tells you how many pixels are in your image� ignore that if you want. It�s like counting the tiles in your kitchen� you can but it isn�t really necessary. First, decide what resolution you want to use� here, I�m preparing this image for printing at 300 ppi. Second, Adjust the image in width and height in inches� checking to make sure the resolution stays.

12. ResolutionHow do I make my images the right size? Set resolution first Set size in inches To review: Set resolution. Set the size in inchesTo review: Set resolution. Set the size in inches

13. File TypesWhy so many? We create letters in one kind of software, but can save in different formats. Why? What is the trade off from one format to another? Images are just the same. We can play with them in one kind of software, but want to save them in different formats for different reasons.We create letters in one kind of software, but can save in different formats. Why? What is the trade off from one format to another? Images are just the same. We can play with them in one kind of software, but want to save them in different formats for different reasons.

14. CompressionMake files smaller and yucky So, you know how to deal with the size of an image� now let�s talk about changing how much memory it takes to store the image. As you may have noticed, photos take up a lot of space. To store them, we can compress them to save space. This is just like those vacuum cleaner bags on infomercials� you stuff something down to make it smaller. You don�t have to have compressed images� after all, it is a trade off� if you compress something, the quality goes down, but the size goes down too. If you leave it uncompressed, the quality is up, but it takes a lot of places to store. Generally speaking, our eyes are pretty forgiving on the web and in low-end printing� but in high-end printing, we need good quality images, so uncompressed is best. TIF can be uncompressed or compressed� you are given the option when saving.So, you know how to deal with the size of an image� now let�s talk about changing how much memory it takes to store the image. As you may have noticed, photos take up a lot of space. To store them, we can compress them to save space. This is just like those vacuum cleaner bags on infomercials� you stuff something down to make it smaller. You don�t have to have compressed images� after all, it is a trade off� if you compress something, the quality goes down, but the size goes down too. If you leave it uncompressed, the quality is up, but it takes a lot of places to store. Generally speaking, our eyes are pretty forgiving on the web and in low-end printing� but in high-end printing, we need good quality images, so uncompressed is best. TIF can be uncompressed or compressed� you are given the option when saving.

15. Saving for Web or eMailgif v. jpg � it�s all in the compression Really, there are two common formats to save images in for the web or email. Remember that web graphics are 72 ppi/dpi. We need two types of images formats, because we have two different ways to make images smaller. GIF reduces the size of an image, by reducing the number of colors. It takes less space to store information about 8 colors in an image, then, say 256 colors. JPG generally reduces the quality of the image. Both GIF and JPG are variable� You can have a high-quality JPG that takes up a little more space than a low-quality JPG. You can also have a GIF with more colors (thus more space) than with few colors. A tutorial on when to use which is at http://www.cahe.nmsu.edu/bchamberlin/photoshop/gifjpeg.htmlReally, there are two common formats to save images in for the web or email. Remember that web graphics are 72 ppi/dpi. We need two types of images formats, because we have two different ways to make images smaller. GIF reduces the size of an image, by reducing the number of colors. It takes less space to store information about 8 colors in an image, then, say 256 colors. JPG generally reduces the quality of the image. Both GIF and JPG are variable� You can have a high-quality JPG that takes up a little more space than a low-quality JPG. You can also have a GIF with more colors (thus more space) than with few colors. A tutorial on when to use which is at http://www.cahe.nmsu.edu/bchamberlin/photoshop/gifjpeg.html