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Reverting images from Photo's back to original file size and quality.

I been searching the forums online seeking info on this but cannot

find the same question or answer to my problem. The images in photos on my Mac

are not as large as the original JPEG’s when they were taken. In an attempt to

get back the best quality I can I am trying to export the photo’s back to the

closest original file size. Most information indicates to select ‘Export

photos in their original format’ to do this. But that gives me the same file

size the image has in ‘photos’ i.e. 1.2MB. But when selecting export as a JPEG

and selecting the maximum size options the image is close to the original of

4.5MB at 4MB. This seem contrary to most information I have read.

Someone else did the original ingest of images to Photo's so is it possible the images

were exported with a lower resolution than the originals in the first instance?



Posted on May 23, 2020 3:27 AM

Reply
Question marked as Top-ranking reply

Posted on May 23, 2020 4:25 AM

File -> Export -> Unmodified Original


That gets out what you put in.


Exporting the same format simply gives you the photograph in the same kind of file.


Size refers to the dimensions of the image - length by breadth, measured in pixels.


File size is determined by the Quality setting. It is, paradoxically, possible to export a file larger than the one you imported in some cases.


To understand how that can happen you need to understand that the Jpeg is not your photo, it's just a compression format applied to your photo. The relationship of Jpeg to photograph is the relationship of shoebox to shoes. Similarly, that Word file is not your novel, it's a container for your work. When you view a jpeg what happens is the file is rapidly decompressed and you can see the photograph. If you then export from Photos (apart from the unmodified original) Photos creates a new file and puts your photo into it - and the size of that file depends on the settings in your export dialogue. The lower the quality the smaller the file. The higher the quality the larger the file. And sometimes, exporting at the Maximum quality setting results in a file larger than the one you imported. This is not because any data has been added to the photograph, just that Photos is applying less compression that your camera did.

8 replies
Question marked as Top-ranking reply

May 23, 2020 4:25 AM in response to A_747s

File -> Export -> Unmodified Original


That gets out what you put in.


Exporting the same format simply gives you the photograph in the same kind of file.


Size refers to the dimensions of the image - length by breadth, measured in pixels.


File size is determined by the Quality setting. It is, paradoxically, possible to export a file larger than the one you imported in some cases.


To understand how that can happen you need to understand that the Jpeg is not your photo, it's just a compression format applied to your photo. The relationship of Jpeg to photograph is the relationship of shoebox to shoes. Similarly, that Word file is not your novel, it's a container for your work. When you view a jpeg what happens is the file is rapidly decompressed and you can see the photograph. If you then export from Photos (apart from the unmodified original) Photos creates a new file and puts your photo into it - and the size of that file depends on the settings in your export dialogue. The lower the quality the smaller the file. The higher the quality the larger the file. And sometimes, exporting at the Maximum quality setting results in a file larger than the one you imported. This is not because any data has been added to the photograph, just that Photos is applying less compression that your camera did.

May 23, 2020 6:04 AM in response to A_747s

The images in photos on my Mac
are not as large as the original JPEG’s when they were taken.

How have the photos been imported to Photos?

Have they been imported with "File > Import"? Have the photos been migrated from an iPhoto Library or Aperture Library?


Have you been running any cleaning applications to remove duplicates and save storage? Such cleaning applications can reduce the quality of your photos by keeping just the low quality preview of an edited version.



May 23, 2020 8:15 PM in response to Yer_Man

When I export unmodified the dimensions are the same as original but the file size is quite a bit smaller.

Exporting as JPEG gets me close to the file size as the original.

The original images were taken as JPEG's and I did not do the original export however.

So when doing the original import if some smaller reduced size was selected is this why the file size is not as large as

the size that is on the original CF card.(I still have some of the originals that is why I trying to get the best quality I can get

for the ones I don't have).

May 24, 2020 12:12 AM in response to A_747s

When I export unmodified the dimensions are the same as original but the file size is quite a bit smaller.


Smaller than what? Where is the file you're comparing it with? Photos (nor any of its predecessors) do nothing to an imported file. It just copies it in. So if it's exporting a 1mb file as unmodified then that's what was brought in.


There is no way to improve the quality of the photograph. But you can reduce the compression by exporting at maximum.

May 24, 2020 12:16 AM in response to A_747s

A_747s wrote:

The photo's that were originally RAW do not revert to RAW when selecting unmodified also.


Then they were not Raw when imported. There is no reverting involved. When you import a raw it always remains a raw. The master file is untouched. Your decisions are recorded in the database and a preview version made, but the master is never touched. If you export an unmodified original then you get out what went in. There is no scenario where importing a raw would yield a Jpeg. You either get a raw or you get a failed export.


You're not using drag and drop are you? Or shooting raw and jpeg pairs?

Reverting images from Photo's back to original file size and quality.

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