Thoroughly confused about file size? I'm hoping someone out there can answer my question. I have two images that are practically identical, but have vastly different file sizes.

Fredrick Loc: Former NYC, now San Francisco Bay Area

I'm hoping someone out there can answer my question. I have two images that are practically identical, but have vastly different file sizes. Attached is the first image. (I tried attaching the second image, but the file size was too large.) The first image has a file size of 3.27 MB, and the second image has a file size of 27.5 MB. In editing this image I was going back and forth between Luminar NEO and Luminar AI. At times Luminar NEO is slow on my laptop and I run out of patience and go over to Luminar AI. The images are "slightly" different from one another but I can't imagine that that would account for the file size difference.
I've looked at the exif data on each image, and they're basically the same, except for one thing. On the exif data for the second image which is 27.5 MB (which I couldn't attach - Luminar NEO) it says "Photometric interpretation: RGB." On the exif data for the first image which is 3.27 MB (Luminar AI) it says "Photometric interpretation: ." So, it has something obviously to do with that? I've done Google searches on Photometric interpretation but can't figure out what that really means and why it's different in both images.
Color Representation in both exif files says sRGB. Any help on figuring out what's going on would be greatly appreciated! Thanks in advance.

(Download)

BebuLamar

Is the other image also a JPEG?

Fredrick Loc: Former NYC, now San Francisco Bay Area

BebuLamar wrote:

Is the other image also a JPEG?

Yes. The exif data for both images is identical with the exception of the field Photometric interpretation.

joecichjr Loc: Chicago S. Suburbs, Illinois, USA

Fredrick wrote:

I'm hoping someone out there can answer my questio... (show quote)

An astonishingly beautiful composition that is literally breathtaking 🌈🌈🏆🌈🌈

Haydon

If they're both identical in measurements in L/W and are both jpg's, I would suspect it has to do with jpg compression.

Fredrick Loc: Former NYC, now San Francisco Bay Area

Haydon wrote:

If they're both identical in measurements in L/W and are both jpg's, I would suspect it has to do with jpg compression.

I just noticed in the exif data that the first image which is 3.27 MB says Compression is (blank), whereas the second image exif data for the 27.5 MB file says Compression: JPEG.

I don’t understand why that would be (perhaps different settings in Luminar NEO vs. Luminar AI?), and what the implications might be?

CHG_CANON Loc: the Windy City

Fredrick wrote:

Yes. The exif data for both images is identical with the exception of the field Photometric interpretation.

We'll have to trust your too large to attach file is also 5118x3412px. The EXIF of the post doesn't include any values for 'compression'. I'd look at how the JPEGs were compressed.

Other questions, since multiple software are involved: how was the image captured? What edit colorspace? What format changes occurred, such as RAW to what to what to this JPEG?

Fredrick Loc: Former NYC, now San Francisco Bay Area

CHG_CANON wrote:

We'll have to trust your too large to attach file is also 5118x3412px. The EXIF of the post doesn't include any values for 'compression'. I'd look at how the JPEGs were compressed.

Other questions, since multiple software are involved: how was the image captured? What edit colorspace? What format changes occurred, such as RAW to what to what to this JPEG?

Yes, they’re both 5118X3412px.

CHG_CANON Loc: the Windy City

Fredrick wrote:

Yes, they’re both 5118X3412px.

You're stuck trying to recreate the processing steps, playing close attention / inspection of each new file and / or file-save in the process. Stating the sRGB encoding of the colorspace is likely not the difference in byte-size of two JPEGs.

Fredrick Loc: Former NYC, now San Francisco Bay Area

joecichjr wrote:

An astonishingly beautiful composition that is literally breathtaking 🌈🌈🏆🌈🌈

Thanks.

Fredrick Loc: Former NYC, now San Francisco Bay Area

CHG_CANON wrote:

You're stuck trying to recreate the processing steps, playing close attention / inspection of each new file and / or file-save in the process. Stating the sRGB encoding of the colorspace is likely not the difference in byte-size of two JPEGs.

I had a 16X24 print made at BayPhoto with the 3.27MB file, and it came out beautiful. If I could figure out how I basically turned a 27.5MB file into a 3.7MB file and be happy with the large print results I could save a lot of file space.
I’ll try to recreate my editing steps.

CHG_CANON Loc: the Windy City

Fredrick wrote:

I had a 16X24 print made at BayPhoto with the 3.27MB file, and it came out beautiful. If I could figure out how I basically turned a 27.5MB file into a 3.7MB file and be happy with the large print results I could save a lot of file space.
I’ll try to recreate my editing steps.

Larger files in bytes of storage, alone, does not mean a difference in the viewing nor print attributes of the file. Most issues related to pixel-based images start and end with the pixel resolution of the file. Then there's the colorspace, and finally, the level of JPEG compression.

I've been discussing the supreme importance of pixel resolution and JPEG compression (aka quality) for years: Recommended resizing parameters for digital images

Colorspace too: What happens when you set your camera to Adobe RGB?

Fredrick Loc: Former NYC, now San Francisco Bay Area

CHG_CANON wrote:

Larger files in bytes of storage, alone, does not ... (show quote)

Yes, I have read your articles, and will read them again. Thanks.

TriX Loc: Raleigh, NC

Regardless of the solution to the problem, it IS a lovely image.

Fredrick Loc: Former NYC, now San Francisco Bay Area

TriX wrote:

Regardless of the solution to the problem, it IS a lovely image.