Size of an image
Nov 18, 2019 15:06:27 #
Rongnongno wrote:
May I remind you that the question includes the fo... (show quote)
Ron, I was responding to "bleirer" in that last post. An image file has height and width pixel information and when a PPI is included in that file the dimensions can be calculated. While technically a data file is in itself dimensionless, for practical purposes the file does have size.
Nov 18, 2019 15:15:47 #
Rich1939 wrote:
Ron, I was responding to "bleirer" in that last post. An image file has height and width pixel information and when a PPI is included in that file the dimensions can be calculated. While technically a data file is in itself dimensionless, for practical purposes the file does have size.
Right but the question is not about practical but theoretical. The answer to that question is a simple 'No'.
Can you tell me the dimension of 2x2 with no other data? No. You get 4 but 4 of what?
Nov 18, 2019 15:18:10 #
Rongnongno wrote:
Right but the question is not about practical but theoretical. The answer to that question is a simple 'No'.
Can you tell me the dimension of 2x2 with no other data? No. You get 4 but 4 of what?
Can you tell me the dimension of 2x2 with no other data? No. You get 4 but 4 of what?
I don't disagree, but again, I was responding to another post.
Nov 18, 2019 17:59:15 #
Since you (the OP) have Photoshop, try this: click the triangle in the bottom border of the document window.
Nov 19, 2019 07:10:38 #
Nov 19, 2019 09:28:44 #
garrickw
Loc: Wyoming Mn.
Its easy for printing 300 dpi divide 300 into 2400x850= 8x2.5
some printers will print 240 dpi 240 into 2400x850= 10x3.5
some printers will print 240 dpi 240 into 2400x850= 10x3.5
Nov 19, 2019 11:05:07 #
Oh come on folks the OP asked a simple question give him a simple answer. Here is one way, I'm fairly sure there other simple ways that don't require complex answers.
Open the file in almost any editing program, I use PS go to image size and it will give you the option of the size in ppi, inches or mm.
Open the file in almost any editing program, I use PS go to image size and it will give you the option of the size in ppi, inches or mm.
Nov 19, 2019 13:13:50 #
It's call Mathematics. They used to teach it in Elementary Schools. JK. The serious replies above will help you.
Nov 19, 2019 14:05:52 #
Nov 19, 2019 21:42:57 #
will47 wrote:
This is just an example: if there is a image that is 2400 x 850 pixels is there any way to know the size in inches if I know no other info about this image? Thanks.
Divide the value in the EXIF “dpi” header into both dimensions. In this case, if it is 240 dpi, the image default size is 10” x 3.542”.
THAT SAID, you can make the image bigger or smaller by varying the reproduction dot size. Or, you can interpolate the image larger or sub-sample it smaller... at the same or a different resolution dpi.
Nov 19, 2019 23:23:44 #
burkphoto wrote:
Divide the value in the EXIF “dpi” header into both dimensions. In this case, if it is 240 dpi, the image default size is 10” x 3.542”.
THAT SAID, you can make the image bigger or smaller by varying the reproduction dot size. Or, you can interpolate the image larger or sub-sample it smaller... at the same or a different resolution dpi.
THAT SAID, you can make the image bigger or smaller by varying the reproduction dot size. Or, you can interpolate the image larger or sub-sample it smaller... at the same or a different resolution dpi.
So does a jpeg out of a camera have a native image size or dpi value from the start, and if it does, is that a meaningless number since the same number of pixels can be switched to any resolution without resampling?
Nov 19, 2019 23:41:25 #
Nov 19, 2019 23:46:28 #
Mickey Finn wrote:
I drive a Conon 7Dll and 5d III. Both have JPEG size settings.
I don't mean the file size/quality of jpeg, rather the dpi or image size.
Nov 20, 2019 09:20:56 #
garrickw
Loc: Wyoming Mn.
the size of the jpeg out of the camera before processing should be 300dpi so if the camera produces a size of 12x18 inch size that would be at 300dpi
Nov 20, 2019 12:09:00 #
I think I leaned a little something about this dpi. This helped. https://www.dpreview.com/forums/post/29164590. So a file might have a dpi in the exif as well as an indication of the number of horizontal and vertical pixels, but that could be used, ignored, or over ridden by whatever software is displaying or printing the image. Without resampling the image pixel count is not changed, so you send a file to a printing service for an 8 by 10 and for a 16 by 20 the service is doing its own math based on the pixel count, not what the exif 'suggests.'
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