General Settings
© 2017 Mark Hickenbottom
|
![]() 300dpi | ![]() 400dpi | ![]() 600dpi |
![]() | ![]() | ![]() |
![]() 300dpi | ![]() 400dpi | ![]() 600dpi |
![]() 300dpi | ![]() 400dpi | ![]() 600dpi |
shown with a width of 180, normal size for 600dpi | |
![]() beauty, 600dpi | ![]() the beast, 300dpi |
shown with a width of 90 normal size for 300dpi | |
![]() beauty 600dpi | ![]() the beast 300dpi |
Image Formats |
TIFFs
|
TIFFs are often used for scanning, editing, printing, or archiving high quality images. EU's Succeed report on formats recommends TIFFs (uncompressed or LZW compression) for the preservation of still images. To retain all image quality, TIFFs normally use no compression or LZW or ZIP lossless compression. JPEG lossy compression is rarely used for obvious reasons. LZW is commonly used and works well with 24-bit images, but works poorly with 48-bit images. ZIP is slightly better at compressing images, but is newer and less commonly supported. Both LZW and ZIP compression greatly increase the save time for 24-bit images. Pixel Order is a TIFF option set to Interleaved or Per Channel (aka Planar). Interleaved is the normal arrangement of pixels from first to last, with each pixel having a red value, green value, and blue value in that order (RGBRGBRGB). Per Channel rearranges the pixels by color channel, starting with all of the red values of all the pixels, followed by all the green values, and ending with all the blue values (RRRGGGBBB). Supposedly, Per Channel helps a little with compression, but is not widely supported. Byte Order is a TIFF option designed to support the Endianness of the target CPU, either Intel (PC) or Motorola (Mac). Not only should this option be obselete (as both PC and Mac computers use Intel CPUs now), but virtually all modern programs support either Byte Order on any type of computer. |
---|---|---|
JPEGs
|
JPEG is a popular format for photographic images on the web because of their small size. To achieve such a small file size, JPEG files use lossy compression. The degree of compression is selectable anywhere in a broad range from low to high. A low degree of compression results in a small file size and virtually no noticeable change to image quality. A high degree of results in a much smaller file size and significant loss in image quality. Quality is lost because some image details are permanently discarded to save space. Even more quality is lost due to generation loss, which occurs every time the image is opened, edited, and re-saved. |