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>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 We

by sirn 14y ago

>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): 330090 1.jpg 329916 2.jpg 329898 3.jpg

ck2 14y ago
Yup, jpegtran is a must for post-processing adobe images. It can also do a lossless conversion to progressive format. Most people do not know about it though. JPEGOPTIM is another one. You can examine what's embedded in the image here http://regex.info/exif.cgi http://regex.info/exif.cgi but there are better offline tools.
- radley 14y ago
  I don't get it. Why is jpegtran a must?
  - CWIZO 14y ago
    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-with-jpegtran http://hancic.info/optimize-jpg-or-jpeg-images-automatically...
    - radley 14y ago
      It sounds great in theory but the previous example only saved < 200 bytes. That's not really optimization, that's overkill.
      - CWIZO 14y ago
        Not if you have many images on the same page. Then id adds up.
        radley 14y ago
        If you place 1800 images on a page, you'll save enough bandwidth to now have 1801.
    - jseliger 14y ago
      In response to Radley, who said: * 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.

by sirn 14y ago

ck2 14y ago

Yup, jpegtran is a must for post-processing adobe images. It can also do a lossless conversion to progressive format. Most people do not know about it though. JPEGOPTIM is another one. You can examine what's embedded in the image here http://regex.info/exif.cgi http://regex.info/exif.cgi but there are better offline tools.

radley 14y ago
I don't get it. Why is jpegtran a must?
- CWIZO 14y ago
  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-with-jpegtran http://hancic.info/optimize-jpg-or-jpeg-images-automatically...
  - radley 14y ago
    It sounds great in theory but the previous example only saved < 200 bytes. That's not really optimization, that's overkill.
    - CWIZO 14y ago
      Not if you have many images on the same page. Then id adds up.
      - radley 14y ago
        If you place 1800 images on a page, you'll save enough bandwidth to now have 1801.
  - jseliger 14y ago
    In response to Radley, who said: * 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.