IV. SHARPNESSEVALUATION 28
Reviewing Imageson the
Camera’sLCD Monitor
Monitor Evaluation Vs.
Printed Output
The firststep in evaluating image quality for most EOS Digital SLR users is checking the
LCD monitor during Review or Playback. The MarkII cameras are equipped with a zoom
function thatmagnifies captured images up to 10x with a scrolling function to examine
specificdetails. It’s important to understand that the image used for reviewing purposes
isactually a small JPEG (approximately 1,536 x 1,024 pixels) that’s embedded into the
file specificallyfor this purpose. This method drastically speeds up the review process
compared to reading the fullresolution file. The trade-off is that the level of detail is
limited. There’senough data in the embedded JPEG to see (for instance) whether a
subject’seyes were open or closed, or to get a rough idea of focusing accuracy, but not
enough to read extremelyfine detail. In other words, it’s not possible to determine the
actualsharpness of the image by looking at the camera’s LCD monitor only. The next
step towardsevaluating image quality is downloading your images to a personal
computer to view or print.
Mostexperts suggest that the best way to evaluate the quality of a digital image is to
view itat 100% magnification on a high-quality monitor. When the objective is image
editing, thisis good advice. These same experts also point out that average human
vision cannotresolve more than 300 ppi (pixels per inch) for printed output. Using these
specifications, please review the following chart:
Clearly, there isa tremendous difference between image dimensions on screen at 100%
magnification and image dimensionsat 300 ppi. EOS-1 class digital SLRs produce
imagesso large that viewing them at 100% magnification is like viewing a poster-sized
print. Also, keep in mind thatmost people view their monitors at much closer range
than the normalviewing distances for prints. Under these conditions, the image is
IV. SHARPNESS EVALUATION
Camera Model
Max. Resolution Image Dimensions @ 72 dpi
(Screen resolution)
Image Dimensions@ 300 ppi
(Printing resolution)
EOS-1D 4.1MP
(2464 x1648)
34.2 X22.9 inches
(2.8 x1.9 ft.) 8.2 x5.5 inches
EOS-1D MarkII 8.2MP
(3504 x2336)
48.7 x32.4 inches
(4.1 x2.7 ft.) 11.7 x7.8 inches
EOS-1Ds 11.1MP
(4064 x2704)
56.4 x37.6 inches
(4.7 x3.1 ft.) 13.5 x9.0 inches
EOS-1DsMark II
16.7MP
(4992 x3328)
69.3 x46.2 inches
(5.8 x3.9 ft.) 16.6 x11.1 inches