Iv. Sharpness Evaluation; Reviewing Images On The Camera's Lcd Monitor; Monitor Evaluation Vs. Printed Output - Canon EOS-1 Tips And Techniques

Reviewing Images on the
Camera's LCD Monitor
Monitor Evaluation Vs.
Printed Output

IV. SHARPNESS EVALUATION

The first step in evaluating image quality for most EOS Digital SLR users is checking the
LCD monitor during Review or Playback. The Mark II cameras are equipped with a zoom
function that magnifies captured images up to 10x with a scrolling function to examine
specific details. It's important to understand that the image used for reviewing purposes
is actually a small JPEG (approximately 1,536 x 1,024 pixels) that's embedded into the
file specifically for this purpose. This method drastically speeds up the review process
compared to reading the full resolution file. The trade-off is that the level of detail is
limited. There's enough data in the embedded JPEG to see (for instance) whether a
subject's eyes were open or closed, or to get a rough idea of focusing accuracy, but not
enough to read extremely fine detail. In other words, it's not possible to determine the
actual sharpness of the image by looking at the camera's LCD monitor only. The next
step towards evaluating image quality is downloading your images to a personal
computer to view or print.
Most experts suggest that the best way to evaluate the quality of a digital image is to
view it at 100% magnification on a high-quality monitor. When the objective is image
editing, this is good advice. These same experts also point out that average human
vision cannot resolve more than 300 ppi (pixels per inch) for printed output. Using these
specifications, please review the following chart:
Camera Model Max. Resolution
4.1MP
EOS-1D
(2464 x 1648)
8.2MP
EOS-1D Mark II
(3504 x 2336)
11.1MP
EOS-1Ds
(4064 x 2704)
16.7MP
EOS-1Ds Mark II
(4992 x 3328)
Clearly, there is a tremendous difference between image dimensions on screen at 100%
magnification and image dimensions at 300 ppi. EOS-1 class digital SLRs produce
images so large that viewing them at 100% magnification is like viewing a poster-sized
print. Also, keep in mind that most people view their monitors at much closer range
than the normal viewing distances for prints. Under these conditions, the image is
IV. SHARPNESS EVALUATION
Image Dimensions @ 72 dpi
(Screen resolution)
34.2 X 22.9 inches
(2.8 x 1.9 ft.)
48.7 x 32.4 inches
(4.1 x 2.7 ft.)
56.4 x 37.6 inches
(4.7 x 3.1 ft.)
69.3 x 46.2 inches
(5.8 x 3.9 ft.)
Image Dimensions @ 300 ppi
(Printing resolution)
8.2 x 5.5 inches
11.7 x 7.8 inches
13.5 x 9.0 inches
16.6 x 11.1 inches
28