What is a digital darkroom?
These days, photographers use what I like to call a "digital darkroom".
First of all, you don't need an actual darkroom. You can set it up anywhere
you can set up your computer or laptop. All you need is space for a scanner
and camera. There are
no toxic chemicals to mix, set up, or clean up. You don't need to set aside
large blocks of time to feel productive. I'll never go back to a chemical
darkroom. Enlargers and colour processors are expensive and cumbersome.
Colour balancing is difficult-- you have to keep working at it to keep in
practice. There is a relatively long time between exposing and evaluating
the print: wet prints out of the processor have a blue cast that makes them
difficult to judge. Manipulations -- dodging, burning, contrast control,
colour balancing -- can be done with far more precision digitally --
especially with colour. I'm sometimes tempted to go back to black and white
darkroom printing. It doesn't have the frustrating complexities of colour,
and a well made selenium toned silver print is archival and still hard to
beat. But the new printers comes very close, and digital offers superior
printing control. The results are excellent and getting better.
A digital image is a rectangular grid of pixels, or "picture elements,"
which consist of 8 bits (1 byte) for a Black and White (B&W) image or 24
bits (3 bytes) for a colour image-- one byte each for Red, Green and Blue
(RGB). 8 bits corresponds to 28 = 256 tonal levels (0-255). 16 bit B&W and
48 bit colour (3x16) image formats are also available. They can represent
216 = 65536 tonal levels. An image's resolution is the total number of
pixels, e.g., 1600 x2000 = 3.2 Megapixels, which corresponds to 3.2
Megabytes inside your computer for an 8 bit B&W image or 9.6 Megabytes for a
24 bit (3 byte) colour image. Some image editing programs define image
resolution by physical size for a specified pixels per inch resolution.
Confusing! The total number of pixels is what really counts. That's the
beauty of Photoshop Elements. It simplifies most tasks by automating many of
the most common ones.
There are several popular file formats for storing your images. PSD files
are native to Photoshop (identified by the .psd extension) and I always save
and print my master images in this format. TIFF files (identified by the
.tif extension) are usually uncompressed: a 1600 x2000 pixel 24 bit colour
image requires the full 9.6 Megabytes. TIFF is highly versatile; it can also
save 16/48 bit images. TIFF is the format of choice for saving high quality
images. GIF (.gif) and JPEG (.jpg) files, which are used for Internet
display or emailing, are compressed and usually involve some loss of quality
and detail. JPEG is best for photographic images and GIF is best for block
graphics and charts. JPEGs are typically 1/5 to 1/20 the size of TIFFs,
depending on their quality level (which you can select when you save the
image) and detail. You can change the file extension using the "save as"
command in the file menu.
Digital images are obtained from digital cameras or by scanning film or
prints. Scanners are specified by their dpi or ppi resolution -- dots
(actually, pixels) per inch they can obtain from the source. Scanning the
original source -- the negative or slide -- always produces better quality
than scanning a print. Printers are specified by their dpi (dots per inch)
resolution, typically 720, 1440 or 2880 for Epson. This number is the
stepper motor pitch, not the actual visual resolution. Don't worry about the
correspondence between image pixels and printer dots. This will be handled
by your image editor and printer driver software. It typically requires
several printer dots to represent one image pixel. An image printed at 200
or more pixels per inch can look very sharp. 150 or fewer image pixels per
inch can look fine on large prints, 11x17 inches or more, which tend to be
viewed at greater distances than small prints.
That sums up why we do things in a specific way. Lets move on to our Digital
Editor of choice ... Adobe Photoshop
Elements. |
