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Optimise pictures for Web site #1
Graham Parker's picture
by Graham Parker
November 11, 2010 - 8:28am

Hi
I am helping a friend with pictures for their web site and they are ready to upload all the pictures of their products they are going to sell. I had a look at their site and it is sooooooo slow. the only thing I can think of causing this is the full size jpeg that they uploaded.
Can, when exporting from aperture 3, I make them into lower res jpeg files. Is it the dots per inch or something else
Thanks
Graham

PhotoJoseph's picture
by PhotoJoseph
November 11, 2010 - 8:32am

Graham,

When you export the photos, you have a long list of available preset sizes to export to, and you can create your own presets as well. Whatever the column width of his site is, is the maximum he should be exporting the photos. For example on this site, all photos are 560 pixels wide. On my photo blog at ConfessionsOfATravelJunkie.com all photos are 800 wide.

Sizing exactly to the right size, and then compressing as much as you can while still retaining an acceptable quality (i.e. try JPG 7 or 8, not 9 or 10), helps tremendously, too.

-Joseph @ApertureExpert

@PhotoJoseph
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PhotoJoseph's picture
by PhotoJoseph
November 30, 2010 - 2:31pm

Pix in Pix,

You’re absolutely right, it can be hard to tell on some images. JPEG artifacting will show up in big gradients first, like a nice clear blue sky. Shadows fall apart quickly and you lose shadow details.

One way to see exactly what’s lost is to stack the two images in Photoshop, and apply a Difference algorithm to the top layer. Anything that’s not exactly the same between the two layers will show up as a color.

-Joseph @ApertureExpert

@PhotoJoseph
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Graham Parker's picture
by Graham Parker
November 12, 2010 - 6:57am

Hi Joseph
Thanks for the quick response as usual. I understand what you mean there is also an option for DPI should I set that at 72
Thanks again

Graham

PhotoJoseph's picture
by PhotoJoseph
November 12, 2010 - 7:07am

Graham,

DPI is only relevant when printing. But yes, set it at 72, that’s fine.

cheers
-Joseph @ApertureExpert

@PhotoJoseph
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Pix In Pix's picture
by Pix In Pix
November 30, 2010 - 1:53am

I tend to export jpg files at a quality of between 5-7 and at 72 dpi.

Side by side I struggle to see any difference in quality from a jpg exported at 5 or 10 quality, the file size however is very much changed. Averaging around 500kb for a file quality of 10 and only 60kb for a file exported at quality 5.

Export a few different versions and decided for yourself as sometimes image content can change things a bit.

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