I rarely use photoshop myself - I learned it from having to support photoshop users and solve why the images they upload to the CMS system were so massive, ie. 400k for a 600x600 photo
What we did for the non-tech people was simply tell them to always use setting #6 on photoshop and use the progressive setting. Two steps seemed the most they could handle.
I had to go into photoshop and save the same image repeatedly under all the different settings and then examine the resulting jpeg under different tools to see exactly what it was doing.
It also doesn't help that photoshop bloats jpegs by adding hidden adobe meta to every jpeg (beyond and different from exif).
Here is a technical analysis someone did on the photoshop settings:
>It also doesn't help that photoshop bloats jpegs by adding hidden adobe meta to every jpeg (beyond and different from exif).
I believe if you use "Save for Web", it will strip out most metadata and EXIF from the image before saving. Here's a result of using "Save for Web" (1.jpg), passing through JPEGTRAN with `-copy none -optimize` (2.jpg) and `JFIFREMOVE` (3.jpg):
Because it strips any meta information contained in the file which reduces file size. It can also losslessly optimize the image. See here for details (I've written about it a short while ago): http://hancic.info/optimize-jpg-or-jpeg-images-automatically...
* It sounds great in theory but the previous example only saved < 200 bytes. That's not really optimization, that's overkill.*
That's a fair point, but if you've got a site that's getting hundreds of thousands or millions of views, or a large number of thumbnails, the one-time effort to shrink image size might be worth it.
how does this translate into something like ImageMagick ? I mean, if I have users uploading large (>10mb) images which I want to transform into web-optimized images, is there a server-side pipeline that would give the most meaningful results ?
What we did for the non-tech people was simply tell them to always use setting #6 on photoshop and use the progressive setting. Two steps seemed the most they could handle.
http://i.imgur.com/vct3D.png (best one-shot photoshop settings for web jpegs)
I had to go into photoshop and save the same image repeatedly under all the different settings and then examine the resulting jpeg under different tools to see exactly what it was doing.
It also doesn't help that photoshop bloats jpegs by adding hidden adobe meta to every jpeg (beyond and different from exif).
Here is a technical analysis someone did on the photoshop settings:
http://www.impulseadventure.com/photo/jpeg-quantization.html...