I usually shoot with RAW or Large jpeg and eventually post most of my photos in a slideshow on my website. Recently I was running out of diskspace and changed my camera setting to Medium jpeg. I was surprised at the difference, it produced a better photo on the web. Is there such a thing as too large when shooting for web? I'm begining to wonder if shooting the smallest jpeg setting might produce a better web shot because of less compression. Any comments appreciated.
The "standard" for a web image 72ppi. Most monitors don't perform any better with a higher res image - all it does is cause a longer download time for the enduser. However it is not unusual for folks to upload images in the 96 (or higher) ppi if they know the typical viewer of their work can benefit. If you are loading a large image, again a larger ppi may benefit the person viewing it.
Finally, a lot of forums only allow a max of 800-1200 pixels on the longest side. Otherwise it is hard to view the image in a browser without scrolling. Obviously your own site can have whatever size you want, but give folks the option of something smaller if they need to.
RE: JPEG - Whatever compression that maximizes quality but meets the criteria above is one the one to use.
Edited by jdryan3 on Feb 25, 2008 at 11:28 PM GMT (Reason: Bad typo on dpi - should have been ppi (doh!))
mikekel wrote:
I usually shoot with RAW or Large jpeg and eventually post most of my photos in a slideshow on my website. Recently I was running out of diskspace and changed my camera setting to Medium jpeg. I was surprised at the difference, it produced a better photo on the web. Is there such a thing as too large when shooting for web? I'm begining to wonder if shooting the smallest jpeg setting might produce a better web shot because of less compression. Any comments appreciated.
It sounds like you might be confusing the size of the original image (as shot) and the size posted on the web. Do you resize/resample the images before posting on your site?
Mike, not sure what you are saying. It matters not what image file size your camera is set at, you will still need to reduce to 72 dpi and around 800 pixels on the long side in post processing for web presentation. Try Fred's WP Pro.
The 72ppi standard used on the orginal Macintosh computers, the first with WYSIWYG fonts, were a carry-over from manual typesetting where the points and picas are the standard units of measure. There are 72 points per inch (ppi) and 12 points per pica.
The term DPI or "dots per inch" originated in first in letterpress printing to describe the screen ruling used for halftones, which in the good old days were chemically etched into copper plates. Newspapers were typically 75-80 dpi. Magazines 133 dpi. Offset printing allowed finer screening, most commonly 150 dpi. 150 is a "magic" number perceptually because at 150 dpi the human eye will perceive a screened image as continuous tone at normal reading distance. 300 ppi was the resolution of the first Postscript laser printers which arrived on the scene shortly after the Macs. Laser printers, like offset printing, used screen halftones. The 300 ppi laserprinter resolution followed a commonly used rule of thumb in printing to use an output resolution which was 1.5x - 2x the desired screen ruling. Each variable sized "dot" on a 300 dpi laser printer spaced 1/300th of an inch apart is actually formed by an 8 x 8 matrix of smaller dots to create the range of tone from white (plain paper) - to 50% gray (4 of 8) to 100% (8 of 8). So a "300 dpi" laser printer actually is printing a pattern of 8 x 300lpi or 2400ppi tiny toner spots on the paper. Ink jet printers use stochastic (random pattern) screening so there are no regular angled dot patterns as with offset printing. Output resolutions for ink jets (e.g. 300 ppi) address how how large the print will be.
Regarding the OPs question, file size and compression are two entirely different variables affecting quality. The best resolution for a file is the largest pixel dimensions the camera can capture. When smaller dimension files are stored in the camera the camera resample and "throws away" captured detail to make the dimensions physically smaller - not a good thing. JPG compression affects how the colors similar colors are averaged when compressed. Again the highest level is best when capturing the images in the camera. It's best to capture RAW in camera.
When you resize for the web in Photoshop the primary consideration is how big a monitor you expect the audience to own, or more precisely what pixel dimensions they define in the display set-up. 600H x 800W is commonly used. When you get larger than that some with smaller monitors might need to scroll to see the entire image. Level 8 quality level is sufficient for most images. Higher values greatly increase file size without a proportionate increase in quality which can be seen. Just save the same image at various compression levels an compare. Equally critical is how sharpening is applied. Do the sharpening as the last step, after resizing.
jdryan3 wrote:
So right, so right! Bad brain fart on my original post - ppi, NOT dpi. Post has been edited.
For web viewing it still doesn't matter - 72 or 96 or whatever number in whatever units - ppi or dpi. Only the size (width and hight) in pixels matters.
Jeffrey wrote:
My advice was not bad. The 72 dpi part may not have been necessary, but it helps determine actual size.
Regarding the quality of web images, the only size measurements that matter are the image dimensions, such as 640 x 480 pixels. As far as the web goes, that is the "actual size" of the image. (Jpeg quality settings obviously matter too, but they affect a different size measurement, the size of the image when stored on disk, such as 150k.)
DPI has no relevance whatever to sizing for the web. It is useful only when sizing for a printer.
I do resize before they go to the web and actually the slideshow generator does it. I know this doesn't make a lot of sense, I was just surprised that shots taken at a lower resolution somehow ended up looking better on the web after resizing. Thanks for the reply.
Thanks for all the responses. I concluded I need to review all my settings from photo to screen. Digging into the software (DPP, jalbum, frontpage) and camera settings exposes numerous opportunities to accidently alter settings. Between camera, DPP and jalbum are three different sharpening options.
mikekel wrote:
I was just surprised that shots taken at a lower resolution somehow ended up looking better on the web after resizing.
"Somehow" is where the answer lies. The difference surely isn't in the original images. Somehow, while processing, you are inadvertently degrading the quality of the hi-res shots. Figure out what that is and the puzzle will vanish.
correct, I discovered thru my workflow there are sharpening options in 4 different stages, three of them not very obvious. Taking a large image, compressing it and applying sharpening (unintentionally) generates a grainy looking image. Thanks for all the replies.
