Hamilton College Digital Collections


Table: Specifications for Digitizing Photographs (black and white, grayscale and color)
Use Resolution Bit Depth Color Space Dimen-
sions
Editing/
Processing
File Format/ Compression Storage

Archival
Master
(AM)

Long-term archive

600 ppi1

24-bit

RGB

At least 4,000 pix on LS

Check grayscale2 and color accuracy3

TIFF, with little endian (IBM PC) Byte Order; no compression; save with embedded ICC Color Profile

Stored on 2 media: CD, DVD, tape, spinning disk

Working
Master
(WM)

-To create derivatives.

-Publication printing.

sRGB



-Change file format.4
-Saved as sRGB

-Tone & color adjusted

-Sharpened

Same as AM, but may be compressed with LZW compression if saving storage space is essential.5

If kept, same as AM.

Static
Delivery File

Internet delivery

150 dpi
(range: 72-200 dpi)

W: 640 px
H: 480 px
Zoom:
W: 640+ px
H: 480+ (zoom)

-Reduced dimensions
-(Converted to grayscale if b&w.)

-Sharpened

JPEG, medium quality, 5-7; or high quality, 8-10 (of 10)6

Spinning disk and backup tape

[1] - Increase resolution for small photos if necessary in order to achieve 4,000 pixels on the long side. If the original material is larger than 8 x 10 inches, see Digitizing Oversize Objects.

[2] - Grayscale factors: minimum number of visible steps: 18; minimum number of f-stops: 5.5; Y channel noise: <=5%.

[3] - Color accuracy: DeltaE < 8, ICC Profile (decrease if image is very large).

[4] - If you are using Photoshop to edit the Working Master, change the file's TIFF format to PSD, Photoshop's native file format, which allows for more editing functionality.

[5] - To provide zoom and pan functionality for an image, you can upload the Working Master (TIFF) file to a "full resolution" CONTENTdm collection. CONTENTdm will then convert the TIFF format to a JPEG2000 format. [See Submitting Full-resolution Images.]

[6] - This dimension is used to achieve optimal viewing of an image in HDR. Providing more pixels on the long side, say 1200 pixels, increases its size and will require the user to select an option to enlarge it for full viewing

(Updated: May 6, 2008, December 17, 2010, pjm)