Get the Best Digital Images Possible. What s it all about anyway?

Transcription

1 Get the Best Digital Images Possible What s it all about anyway?

2 Issues to Consider Resolution Image Size File Size Intended Use of the Image File Formats

3 Issues to Consider Image size (width and height pixel dimensions) Pixel dimensions of original image determine how large the finished product can be without degrading the image quality

4 Issues to Consider File Size Larger file sizes cause slower page loading for Web pages Longer print times for printed images The more pixels in an image the larger the file size

5 Issues to Consider What s the intended use of the image? Print Print dimensions are more important than pixel dimensions Higher resolutions produce better quality printed image Online viewing File size is the most important consideration Pixel dimensions determine approximate viewing size

6 Resolution What IS resolution? Ability to resolve detail (changes in contrast between pixels) More commonly used to describe total number of pixels in captured image The greater the number of pixels captured, the better the resolution but More pixels means larger file sizes

7 Types of Resolution Image Resolution # of pixels per unit of length measured in pixels per inch (ppi( ppi) A high resolution image contains more pixels than an image of the same dimensions with a low resolution

8 Types of Resolution Monitor Resolution # of pixels per unit of length on a monitor measured in pixels per inch (ppi( ppi) Image pixels translate directly into monitor pixels If image resolution is higher than monitor resolution, image appears larger on screen than it prints

9 Types of Resolution Common Monitor Resolutions 640 X X X X 1024 Newer monitors can have even higher resolutions

10 Types of Resolution The same image displayed at two different monitor resolutions will appear at different sizes The monitor s physical size also influences the size the image appears at

11 Types of Resolution An image displayed on a 19 monitor set to display 1024 X 768 pixels looks much larger than the same image displayed on the same monitor at 1280 X 1024 pixels

12 Types of Resolution Output or Printer Resolution # of ink dots per inch produced by printer measured in dots per inch (dpi) Higher resolution printers combined with higher resolution images generally produce the best quality

13 Print Resolution Appropriate resolution for printing is determined by both the printer s resolution and the screen frequency (lines per inch lpi) ) of the halftone screens used by the printer to produce images

14 Getting the Right Print Resolution Computer Graphics Rule of Thumb: Scan image at 1.5 to 2 times the screen frequency used by the printer Screen frequency is usually 133 lpi 133 lpi x 1.5 = 200 ppi correct scanning resolution to use

15 Digital Cameras Camera resolution is measured in terms of the maximum number of pixels the image sensor is capable of capturing Megapixels 1 megapixel = 1 million pixels 3.1 megapixel camera produces images with 2048 X 1538 pixel dimensions

16 Digital Cameras Assume you need at least a 150 ppi image resolution for good print quality To get a good 4 X 6 print you need to capture at least 600 X 900 pixels (150 X 4, 150 X 6) For 8 X 10 print you need at least 1200 X 1500 pixels

17 Digital Cameras Some cameras have multiple resolution settings (pixel dimensions) available Use lower resolutions for smaller file sizes if you don t need to enlarge the image for printing

18 Image Size Best to create the image at the final size you want to use You can always resize images smaller without loss of quality Resizing the image larger later can degrade image quality

19 Image Size Digital Cameras Start with camera set at highest resolution setting if you ll need to print a larger image Use image editing software to resize print dimensions/increase image resolution If image will be used on Web page, reduce the camera resolution setting to reduce the file size and image dimensions when viewed on screen

20 Image Size Scanners Set scanning resolution as high as necessary Scan at higher resolutions for both print and online viewing for best quality Choose the desired print dimensions before scanning Best to scan larger and rescale smaller, than to scan small and then try and resize larger

21 Image Size If you ve scanned at a higher resolution ( dpi): If image is to be used online, use image editing software to lower image resolution to ppi Image detail captured by higher resolution scan will still be there, but file size will be smaller Improves quality of images printed from Web pages

22 File Formats JPEG (.jpg jpg) ) Joint Photographic Experts Group Image is automatically compressed so file size is smaller as camera saves the image as a JPEG file Most digital cameras use the jpg format by default Some cameras use a proprietary file format you ll need to convert to useable formats using image editing software

23 File Formats When editing JPEG images, save in another format while editing each time you resave a JPEG image you lose more data, lowers image quality

24 File Formats Many digital cameras have different quality settings Hi usually uncompressed TIFF files Fine lowest compression JPEG file, larger file size Normal more compression, smaller file size Basic most compression, smallest file size Each setting compresses the image with more or less loss of data affects file size and image quality, not image resolution

25 File Formats Most scanners allow a choice of different file formats to save the final scanned image Choose the format that s best for the intended use of the image JPEG is best for online images due to image compression smaller file sizs TIFF is often best for printing images no image compression, no loss of data

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