Crop command increases file size when cropping iphone jpeg photos

[John Oreopoulos]

I have a question about a certain ImageJ behaviour I have observed recently:

When I open a .jpeg image - specifically a photograph acquired with my iphone - when I crop the image to some arbitrary ROI, the file size increases dramatically. For example, if the original image is only 3.2 MB in size, after cropping, it can jump to 13 MB. What is the cause of this behaviour? Is this a bug?

John Oreopoulos
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[Glen MacDonald-2]

Hi John,
How are you saving the cropped image?  Saving in an uncompressed format may preserve the expanded size of the JPEG.  
Regards,

Glen MacDonald
        Core for Communication Research
Virginia Merrill Bloedel Hearing Research Center
        Cellular Morphology Core
Center on Human Development and Disability
Box 357923
University of Washington
Seattle, WA 98195-7923  USA
[phone]
[hidden email]







On Dec 11, 2014, at 11:40 AM, John Oreopoulos <[hidden email]> wrote:

> I have a question about a certain ImageJ behaviour I have observed recently:
>
> When I open a .jpeg image - specifically a photograph acquired with my iphone - when I crop the image to some arbitrary ROI, the file size increases dramatically. For example, if the original image is only 3.2 MB in size, after cropping, it can jump to 13 MB. What is the cause of this behaviour? Is this a bug?
>
> John Oreopoulos
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

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[John Oreopoulos]

My apologies, the problem is really one of opening an iphone .jpeg in ImageJ. The original file size of the iphone photo is listed as a 3.2 MB .jpeg photo (as seen in my mac finder window as well as mac preview application), but when I open it in ImageJ the file size goes up to something like 30 MB. Again, is this normal behaviour?

John Oreopoulos


On 2014-12-11, at 2:40 PM, John Oreopoulos wrote:

> I have a question about a certain ImageJ behaviour I have observed recently:
>
> When I open a .jpeg image - specifically a photograph acquired with my iphone - when I crop the image to some arbitrary ROI, the file size increases dramatically. For example, if the original image is only 3.2 MB in size, after cropping, it can jump to 13 MB. What is the cause of this behaviour? Is this a bug?
>
> John Oreopoulos
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

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[Gabriel Landini]

On Thursday 11 Dec 2014 15:02:18 John Oreopoulos wrote:
> My apologies, the problem is really one of opening an iphone .jpeg in
> ImageJ. The original file size of the iphone photo is listed as a 3.2 MB
> .jpeg photo (as seen in my mac finder window as well as mac preview
> application), but when I open it in ImageJ the file size goes up to
> something like 30 MB. Again, is this normal behaviour?

Yes. If the file is compressed, when you uncompress to display it regains the
original size on the image container. That is the purpose of the compression:
storing and transmitting.

Cheers
Gabriel

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