When using a high-resolution image, you MUST first open the image in an image-editing or file conversion application and re-save the file in a format other than JPEG. This is a critical step to maintain the quality of the image. Check with your service bureau to determine the best file format for your project.
Technical Specifications - Bitmap Files
The files on this disk have been saved in a variety of convenient formats, canvas sizes and resolutions.
Large and Medium Canvas Sizes
Each file is saved with two canvas sizes: Large and Medium. In general, large-canvas size files are between 28 and 35 MB in file size to accommodate a letter-sized bleed image at 300 dpi. The medium-canvas size files are exactly one-half as wide and tall as their large-canvas size counterparts, making the file sizes about one-fourth as large.
High Resolution and Low Resolution Files
Each large-canvas and medium-canvas image is saved at 300 dpi for high-resolution reproduction and at 72 dpi for position-only placement. The low-resolution files possess exactly the same canvas dimensions as their high-resolution counterparts to provide precise and efficient image replacement when the file is ultimately prepared for high-resolution output.
TIFF and JPEG Formats
The high-resolution versions of both canvas sizes are saved as JPEG files; the low-resolution versions are saved as TIFFs. Both formats are saved in RGB color space. Again, check with your service bureau and/or printer to determine when and how the conversion to CMYK color space should be made.
File Names
Images of either resolution/canvas size can be identified by the first six characters of the file name. The file name suffix identifies the specific resolution and canvas size of the file:
LH.JPG = Large Canvas, High Resolution
LL.TIF = Large Canvas, Low Resolution
MH.JPG = Medium Canvas, High Resolution
ML.TIF = Medium Canvas, Low Resolution
File Compression
Because the high-resolution images are saved as JPEG images, it is important to note a few important features of JPEG compression. While no image degradation is noticeable after a single compression-decompression cycle, subsequent compressions will begin to soften and otherwise degrade the image integrity. To preserve optimum image quality, it is important to never re-save the images in JPEG format. Depending on the target application and operating system, it is best to save the high-resolution images as TIFF, EPS or another format as either uncompressed files or files employing "lossless" compression such as LZW compression.
