About digitized images
You can order a copy of a photograph from the Archives holdings as a digital file.
When you order a digital image, we will send you a CD that contains the following:
- The image in an uncompressed TIFF file
- Documentation in an RTF file
We are unable to email these files.
Digital images measure 3000 pixels along the long edge of the image.
We can create larger images, for example, for maps and architectural drawings. We can also do custom scanning.
The tonal range of some photos has been adjusted after scanning to bring out as much detail as possible. We do not correct colours or fix blemishes, except in rare cases where broken originals — glass-plate negatives — have been digitally stitched together to form a complete image.
Image resizing or reformatting
The Archives provides digital images in the TIFF format only and at the same image size as our master image file.
Any alternations to an image such as cropping, resizing, tonal or colour adjustments, migration to a different file format, or other editing are your responsibility.
Size when printed
The level of detail is equivalent to the detail present in an 8 × 10 printed at 300 pixels per inch. Images are scanned so that an 8 × 10 print could be printed from the file.
How good an image looks when blown up beyond this size depends on a number of factors, including the:
- Quality of the original object the scan was generated from
- Type of printer being used to make the print
- Conditions under which the print will be displayed and viewed
Images are scanned at a minimum of 300 pixels per inch (PPI).
Smaller originals need to be digitaized using a much higher scanning resolution to get the same amount of detail from the image. The Archives uses a scan resoltion that creates a final image measuring 3000 pixels along its longest edge after processing and cropping.
|Size of the original's longest edge||Scan resolution in pixels per inch|
|Larger than 20 cm (8")||400 PPI|
|10 – 20 cm (4 – 8")||800 PPI|
|5 – 10 cm (2 – 4")||1600 PPI|
|35mm film||2400 PPI|
While a scanning resolution can vary depending on the size of the source, the digital image will have approximately the same number of total pixels.
Pixels, DPI, and PPI
A pixel is a short form name for "picture element", which is the smallest discrete component of a digital image. A digital image is formed by an array of pixels that collectively form an image, similar to the way a mosaic is composed of many individual tiles.
DPI is "dots per inch". It is a measure of the density of ink particles a printing device applies to a page, that is, the printer resolution. DPI determines how large a print created from a digital image of a given dimension will appear when printed.
For example, when a digital image 2400 pixels wide × 1800 pixels tall is printed at 300 DPI, the printed image will be 6" wide × 4" tall because the digital image dimensions is divided by the print resolution.
PPI is "pixels per inch", a measure of the image resolution that an input device, such as a scanner, can extract from an image. The scan resolution determines how many pixels will make up the digitized image.
For example, if we scan a printed image that is 4" wide × 5" tall at 600 PPI, the resulting digital image will be 2400 pixels wide × 3000 pixels tall because the printed image dimensions are multiplied by the scan resolution.