File size
The size of a file is determined by whether it is a vector or raster file and whether it is binary, grayscale or color. File compression is a way of reducing file size without compromising image quality.
There are two compression methods: one (called lossless) keeps all the pixels of the original image but finds more efficient ways to represent recurring patterns of pixels in the file; and one (calledlossey) eliminates pixels that aren’t needed to maintain quality.
File formats for printed images
The best file formats to use for images that will be printed are:
Recall that vector images are constructed from mathematical formulas. This means that they are resolution-independent and can be scaled (resized) and manipulated (flipped, rotated, stretched, cropped, colorized, combined) with ease using programs like Adobe Illustrator and Corel Draw. This is an ideal format for initial
design of logos and illustrations, and for clip art.
Raster images are composed of rows and columns of pixels (sometimes called a bitmap). Because raster images are hard to resize and manipulate, they are best used at the size and orientation of the original. Raster images can be cropped, colorized, converted to grayscale or monochrome using image editing programs such as Adobe Photoshop or Corel Paint Shop Pro. All photographs are raster images.
The .tif file format usually produces the best quality image from a digital camera. The other choice is .jpg (Joint
Photographic Experts Group), a file format that has been optimized for continuous-tone full color photographs by incorporating file compression.
JPG compression looks at blocks of 8x8 pixels and selectively reduces the detail in each block. This maintains the physical size of the image, reduces the amount of space required to store it, but sacrifices the quality of the image. The extent of image degradation depends on the degree of compression (it is adjustable).
If you are editing or manipulating digital photographs, work in .tif format rather than .jpg since each new save in .jpg compresses the file. By contrast, a .tif file uses lossless compression, so there is no loss of pixels.
The file formats .psd (Photoshop), .psp (Paint Shop Pro), .ai (Adobe Illustrator) and .cdw (Corel Draw) are proprietary. They are good to use while editing images in order to have access to all the editing tools in the program. However, after the image editing is complete, save raster images as a .tif file and vector images as an .eps file.
Use images successfully
For maximum effectiveness, any image you use in a document must reproduce well. This requires attention to the file format and adhering to production standards.
There are two compression methods: one (called lossless) keeps all the pixels of the original image but finds more efficient ways to represent recurring patterns of pixels in the file; and one (calledlossey) eliminates pixels that aren’t needed to maintain quality.
File formats for printed images
The best file formats to use for images that will be printed are:
- For vector images: .eps (Encapsulated PostScript)
- For raster images: .tif (Tagged Image File Format)
Recall that vector images are constructed from mathematical formulas. This means that they are resolution-independent and can be scaled (resized) and manipulated (flipped, rotated, stretched, cropped, colorized, combined) with ease using programs like Adobe Illustrator and Corel Draw. This is an ideal format for initial
design of logos and illustrations, and for clip art.
Raster images are composed of rows and columns of pixels (sometimes called a bitmap). Because raster images are hard to resize and manipulate, they are best used at the size and orientation of the original. Raster images can be cropped, colorized, converted to grayscale or monochrome using image editing programs such as Adobe Photoshop or Corel Paint Shop Pro. All photographs are raster images.
The .tif file format usually produces the best quality image from a digital camera. The other choice is .jpg (Joint
Photographic Experts Group), a file format that has been optimized for continuous-tone full color photographs by incorporating file compression.
JPG compression looks at blocks of 8x8 pixels and selectively reduces the detail in each block. This maintains the physical size of the image, reduces the amount of space required to store it, but sacrifices the quality of the image. The extent of image degradation depends on the degree of compression (it is adjustable).
If you are editing or manipulating digital photographs, work in .tif format rather than .jpg since each new save in .jpg compresses the file. By contrast, a .tif file uses lossless compression, so there is no loss of pixels.
The file formats .psd (Photoshop), .psp (Paint Shop Pro), .ai (Adobe Illustrator) and .cdw (Corel Draw) are proprietary. They are good to use while editing images in order to have access to all the editing tools in the program. However, after the image editing is complete, save raster images as a .tif file and vector images as an .eps file.
Use images successfully
For maximum effectiveness, any image you use in a document must reproduce well. This requires attention to the file format and adhering to production standards.
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