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Bridge Exports Changes Resolution from 300 to 72 dpi, resizing my image

Mar 16, 2013 12:14 PM

Tags: #export #bridge_cs5

I like to use Bridge (CS5) to export my photographs for printing, and frequently I will use the Export feature to resize the images (e.g., 5x7 vs full size), but every time I export it recharacterizes the images as 72 dpi, vs the 300 dpi I prefer. 

 

Consistent with some of the previous postings (~2 yrs ago) I have seen on this topic the exported images are now "sized" much bigger (29"x20" for what should have been ~5"x7"), and hence expectantly I haven't lost any resolution, but it's aggrevating to have the dpi changed.

 

 

Can anyone tell me how to export without having the dpi changed?

And while I'm at it, can anyone confirm that I'm not loosing image resolution?

 

Thanks so much!!

 
Replies
  • Omke Oudeman
    4,001 posts
    Nov 27, 2004
    Currently Being Moderated
    Mar 16, 2013 2:35 PM   in reply to bhillmar

    Can anyone tell me how to export without having the dpi changed?

     

    Can't find any other settings to change and just having tested it I can confirm that it sets ppi (it is pixels per inch -ppi- for a digital file which is made from pixels and dots per inch -dpi- from the ink dots of a print ) to 72.

    And while I'm at it, can anyone confirm that I'm not loosing image resolution?

     

    You already stated yourself that you did not loose pixels, therefor the size of the files stays the same. It is just a mater of figures. 300 ppi means a larger concentration per inch and 72 pixels per inch means a smaller concentration of pixels per inch. Given the same amount of pixels for both settings this means a smaller image dimension for 300 ppi and a larger image dimension for the 72 ppi.

     

    300 ppi is some 'magic' number from printed press, but it really depends on the need of the job related printing machine. If you have a small image and need to look closely it should have a larger concentration per inch to reflect its sharpness.

     

    However theoretically you would almost have the same visible quality when printed on 72 at billboard sizes. That's because you always have a large distance between your eyes and the bill board. If you look closely you will see the dots (because the billboard is a product of ink dots…) but of course it is not meant to study at that close range.

     

    The same is for judging sharpness on your computer. Ideally you do so at 100 % for correct judgement at real size pixels. But in reality there will be almost no situation you will study a print at that same distance

     

     

    Any thoughts on why these would be different?   And am I fretting over things unncessarily?

     

    Only guesses, the use a different algorithm or calculation scheme, in my case I tried a Canon Raw (converted to DNG) without any ACR settings then the basics applied and found that Bridge export jpeg 11 creates larger files then using PS.

     

    But there are some other concerns I have and that certainly would make me fretting in use of export module:

     

    First of all I almost never use it, merely in this cases for testing, because using the menu tools give a shortcut to Photoshop / Batch and inhere I have created several dedicated resizing and resaving actions that also places the files in preset folders.

     

    But with this small test I found out that

    a: it changes ppi to 72 ppi, not a very big deal but I did not asked for it nor did I wanted it.

    b: it converts my Adobe RGB color space to sRGB and I certainly did not want that without my explicit wish for this conversion, so this is more then a bit worrying to my concern.

    c: it seems to apply a sharpness that I certainly did not want to happen without my knowledge, and this rules the use of the export module out completely.

     

    Since I only tried a DNG file without settings or retouch/developing  in Photoshop the jpeg generated by PS was not very sharp. This makes sense to me because I have set my basic ACR to apply sharpening only to preview. There are a lot of different sharpening theories around but I use one in PS itself. So I was a bit shocked to learn that the export module did all those for me unwanted and not adjustable settings putting me completely out of control…

     

    So if you want to have full control about things happening under the hood yourself just start creating actions in PS, it is very easy to record an action and even more easier to play it. Instead of every time dragging files to export module and always recheck the image options (it seems to reset itself always to jpeg quality 8 on my system) only select the files you want to resize and choose menu tool / Photoshop Batch and select the wanted action. hit OK and your almost done, PS does the rest.

     

    The great thing of the latest PS CS6 action pallet is the extension with a so called 'insert conditional' that let's you create an 'if - then else' action for both landscape and portrait resizing actions so you don't need the 'constrain to fit' or 'fit image' option. Just once create an action for both resizing dimensions and then create a new action with insert conditional. choose If image is landscape play action…. / else play action….

     

    It is really a very productive way. I have a lot of actions (organized in sets for better overview) and even one that creates 4 different sizes in 4 different folders using 1 go in Bridge

     
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    Mar 17, 2013 9:29 AM   in reply to bhillmar

    For you information do not use a quality of 7 as there is a qirk in the color compression program.  Here is a quote from a web search "there’s a different compression strategy  used for a quality of 7 compared to 6. Holding the JPEG image quality constant, this change would normally drastically increase the file size of the photograph. However, not wanting to have a giant leap in file size between 6 and 7, Adobe actually reduces the image quality when going from 6 to 7 in order to compensate for the larger file size!"

     

    Another interesting fact found in the article is an explanation of why the quality values go from 1-12 instead of the standard 1-10. They say it’s because the maximum value people are expected to use is 10. For the values 11 and 12 (included for “experimental reasons”), you don’t actually get much noticeable change in image quality, but file size balloons like crazy!"

     

    For the researcher here is an interesting article about the myth of 72 vs 300 ppi.  Note that the author uses dpi throughout the article and should be using ppi in many cases, but this is only a distraction,  and not a distrotion of the message.  http://www.scantips.com/no72dpi.html

     
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    Mar 17, 2013 4:38 PM   in reply to bhillmar

    JPEG quality setting determines the compression you want.  By compression it means how many pixels you want to through away to get the end result.  Even areas of the image like sky and water, compress quite well with little noticable loss.  As you go lower in quality the compression is higher and at some point you start throwing away pixels you need to get a smooth image.  Hence you end up with a pixelated image.  This may or may not be noticable depending on the magnification and the viewing distance.

     

    PPI is pixels per inch.  So if you image is 1000 pixels wide you and the resoluton is set to 100 you will have 100 pixels per inch and the image will be 10 inches wide.  If you do not resample the image (add or subtract pixels when changing resolution) and change the resoluton to 50 ppi you will have 50 pixels per inch and the image will be 20 inches wide (1000/50). 

     
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  • Omke Oudeman
    4,001 posts
    Nov 27, 2004
    Currently Being Moderated
    Mar 18, 2013 6:33 AM   in reply to Curt Y

    as you go lower in quality the compression is higher and at some point you start throwing away pixels you need to get a smooth image.  Hence you end up with a pixelated image.  This may or may not be noticable depending on the magnification and the viewing distance.

     

     

    Here I would like to add that given the current prices of HD or other storage you might consider to keep the original file in PSD and/or maximum jpeg (including a proper stored back up) and compress copies of the original for the wanted destination.

     

    As Curt stated, different methods for different jobs. For instance if you want a copy for email resize it to smaller image and higher quality jpeg instead of not resizing and lower quality jpeg. As long as you keep your original save you can experiment and copy as much as you like :-0

     
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