Jpeg resolution for PC and Mac

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Many recommend publishing web jpegs at 72dpi. But PCs and Macs display
iamges at different resolutions. Will 72dpi work equally well for both,
or is there a better solution? Thanks.

Re: Jpeg resolution for PC and Mac wrote:

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It actually does not matter at all. The browser does not use the resolution
saved in the image file. Unless you override the image dimensions
(WIDTH/HEIGHT attributes of an image element or via CSS), the browser
assumes that the 'natural' size of the image is its pixel resolution mapped
1:1 to the screen pixels. The image resolution is supposed to be used for
this 'natural' size, but browsers do not implement this.

Benjamin Niemann
Email: pink at odahoda dot de
WWW: /

Re: Jpeg resolution for PC and Mac wrote:
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dpi has no meaning in screen design.

For example, I could have a 21" display running at 800 x 600. The DPI
woyuld be something like 50. On the other hand the same screen maybe
running at 1600x1200, with a DPI of around 100. It's meaningless. When
working with graphics for display on a computer (web page or
otherwise), draw it actual size. Pixel for pixel.

Re: Jpeg resolution for PC and Mac

SpaceGirl wrote:
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Thank you and Benjamin for the responses. I do understand this to some
extent, and probably should rephrase my questions and provide more

My images created in Photoshop are intended for inkjet printing and have
very high dpi. I want to display these on web pages with jpegs of much
smaller file sizes *and* the best quality. When Saving for Web in
Photoshop (to create the jpegs), I have the choice to down sample to
either 72dpi or higher. The higher dpi will increase the file size, and
I'm not sure if that will buy me better quality in web pages.

In html/css, the image's width/height dimensions in pixels will be
defined to be exactly equal to the jpeg's width/height dimensions in
pixels. I think that's what you meant by "draw it actual size. Pixel for
pixel", and what Benjamin noted as well.

Will doing so let the jpeg to be displayed with its "natural"
width/height dimensions in pixels, regardless of what the monitor
resolution is? In this context, will a jpeg created at 72dpi or higher
make any difference other than its file size?

My intent is to preserve the jpeg's "natural" pixel dimensions, so that
it won't be degraded from interpolations due to monitor resolution

Re: Jpeg resolution for PC and Mac wrote:
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No, DPI is not relevelant to screen based display. All you need to
worry about is the dimension in pixels. Resize your image in PhotoShop
to something that fits within your web page. Nothing else matters.

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Kind of. Again, you dont have to specify the height and width of images
within your HTML if you dont want to. By default, the browser will
simply display the image "actual size" (size in pixels). Browsers
totally ignore DPI.

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Wont matter. Dont specify the size in your web page (CSS or HTML) and
let the browser display the images as are. If the images are going to
be to big for screen display, resize them first in PhotoShop. Never
*ever* resize an image in HTML. Browser resizing looks awful.

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That's the best plan. If, for example, you ultimately want the user to
print these images, simply hyperlink the on-screen images to the larger
(full size 300 dpi or whatever) images.

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