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Image size question

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I am a newcomer to Alamy and want to make sure my first 4 images meet the Alamy criteria. However I am still a bit confused about the file size and can't find a clear answer on any of the forums. My apologies in advance if this question has been asked before.


In the "Getting Started'/"Prepare" advice it states that the requirement is for an "uncompressed file size of more than 25MB". I understand that to mean that the final jpg as submitted must be 25 Mega Bytes (MB) or larger. Now, I have a Canon 5D Mk3 that produces CR2 raw files of about 25 Mega Bytes in size but when recently processing an image in Photoshop for submission, I noted that, whilst the image size was 125 Mega Pixels, when saved a jpg, quality 12, the resultant file size is just 17 Mega Bytes. There is no way, short of undesirable upscaling of the original image that I can boost the jpeg up to 25MB.


Am I missing something here? Does the image size criteria really mean Mega Pixels not MB?


Thanks in advance for any clarification





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this seems to cause so much misunderstanding. You are slightly misreading the specifications.


The compressed jpeg file must be under 25 Mg. So your uncompressed file size (or OPEN) of 125 mg is OK, in fact it is much bigger than really needed


For full frame sensors, anything over 70 mg is overkill. Perhaps joined up panoramas might best be bigger


The uncompressed or OPEN file must not be less than 24mg.  Make it 25 to be safe

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Most simply said.

Process yor image. Save as an 8 bit tif. Look at file size. As an 8 bit tif, if it is over 24mb, it is safe. Here is where I can look and see if cropping judiciously helps the image. Your camera gives large enough files to do this.

If the image appears slightly soft, resize the image down to something just over 24mb for the 8 bit tif. This sometimes seems to make the image appear sharper. Be careful here, though, don't try to push a truly soft image through or you'll spend time in the sin bin.


Don't worry about the JPEG final size. As mentioned before, that will vary according to whether the image is a simple one or if it has a lot of detail in it. The more detail, the larger the JPEG. The only thing to be concerned with is the size of the 8 bit tif before converting to JPEG.



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