# Export as large file size



## tonyskerl (Nov 16, 2011)

Hello...Just joined and apologies if this is answered elsewhere but i couldnt find it.
*When i export an image that shows eg 12.1mp to my desktop it appears at about 13mb. Im trying to get images above 24mb.Im running LR 2.7.*
CAn you help? Many thanks


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## erro (Nov 16, 2011)

File size depends on two things:
- the number of pixels (width*height)
- the compression or quality

File size alone doesn't necessarily say anything. An image with lousy quality (much compression) but many pixels can have the same file size as an image with great quality (low compression) but less number of pixels.

What do you want? Why is the file size important to you (or someone else)?

Many times, clients and stock agencies and such say that they require images of a certain "weight" (file size). And that can be in the region of 20-50 MB. But you'll find that a normal JPG will never be this big. That's because the requirement is based on uncompressed image data.


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## tonyskerl (Nov 16, 2011)

Robert ...it is for an agency and they want 24mb or more. i shoot in RAW and images are saved on LR as dng.


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## Hal P Anderson (Nov 16, 2011)

Tony,

What image format do the agency want? If they want jpegs, you won't likely be able to meet their requirements. Raw files are whatever size they are, and you have no control over their size.

Like Robert implied, are you sure that they aren't talking about uncompressed data, i.e., the number of bytes the image takes up in RAM?

It seems like cheating, but you could send a TIFF file. They tend to be fairly large.

Hal


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## Jim Wilde (Nov 16, 2011)

The best bet would be to export as a Tif...


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## tonyskerl (Nov 16, 2011)

Hal
Yep they want over 24mb in uncompressed!  How does that translate into mb when im exporting as a jpeg (apologies for my ignorance)

Jim
They are stating they want jpeg   Its Alamy by the way.


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## erro (Nov 16, 2011)

Well, just export your files as TIFF in original pixel "resolution" (don't resize). How many MB is that file? That is the largest you can get, without upsizing, but then upsizing doesn't make any image "better", just "more pixels".

The raw maths are: pixelwidth*pixelheight*3=total image information (the *3 is because you have 8 bits information for the three colors RGB). So if you have a 12 megapixel image with 4000*3000 pixels you have 4000*3000*3=36000000 bytes of image data. Divide that by1024 twice and you get 34,33 MB uncompressed file size.

Translating uncompressed files size to compressed JPG isn't that easy, since it depends on the amount of compression used for JPG.


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## tonyskerl (Nov 16, 2011)

Robert

Just exported the jpeg with pixels increased to 12000 x 7500 which has given me a file of 32.8mb  so thats done it . Many thanks for your help


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## erro (Nov 16, 2011)

Well, that's probably not the solution. Now you have a JPG file where the *compressed *data is 32,8 MB. The uncompressed data for this image is 12000*7500*3/1024/1024=257,5 MB. You have scaled up your image to a 90 megapixel image. Is that what you want to do?

How many pixels (width*height) is your original image?


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## Mark Sirota (Nov 16, 2011)

tonyskerl said:


> Robert ...it is for an agency and they want 24mb or more. i shoot in RAW and images are saved on LR as dng.



What they're asking for is an 8 megapixel file.  That works out to 24 megabytes of image data with 8 bits per color channel.


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## tonyskerl (Nov 18, 2011)

Thanks for all your help.

 Im exporting images as jpeg ,sRGB at 100% quality sharpened for screen. this results in an image of 4256 x 2832


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## tonyskerl (Nov 18, 2011)

Thanks for all your help.
Im exporting images as jpeg ,sRGB at 100% quality sharpened for screen. this results in an image of 4256 x 2832


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## erro (Nov 18, 2011)

4256 x 2832 means 12052992 pixels (12 megapixel). With RGB each pixel have 3 colors, with 8 bits (1 byte) luminance information. 4256*2832*3/1024/1024=34,5 MB real image data. Any JPG file from this image will be smaller due to the JPG compression (it compresses even at 100% quality). However, the real image data is still 34,5 MB. There are still 12052992 pixels in your JPG, no mater what level of compression/quality.


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## tonyskerl (Nov 18, 2011)

Thank you Robert .....  I was just confused because when i look at the "image info"..... it says "_10.9MB on disk (11,409,522bytes)_"


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## erro (Nov 18, 2011)

The size "on disk" I assume is the actual file size of the JPG file. 34,5 MB image data has been compressed to a 10,9 MB file. You may want to try and export this file in many different quality levels (compression levels) and see how it affects file size and image quality. You may also want to export it as a TIFF to see that file size as a comparison.


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## Mark Sirota (Nov 18, 2011)

Also, be aware that the size of the file on disk also includes the metadata, which can vary greatly in size especially if largish things like embedded previews or custom color profiles are included.  The agency doesn't care about the size on disk; they just care about the amount of image data.

That industry confusingly uses "megabytes" as a measure of this; they assume 8 bits per color channel, and 3 color channels, for 24 bits per pixel (or 3 bytes per pixel, which is 3 megabytes per megapixel).  So their request of "24 megabytes" is easily translated to 8 megapixels.


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