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[Fredrik34154496p9l7]

Hello,
I am a new Lightroom user.
My question is.
I have a B&W negative jpg image of 15228kB
I run this image through Negativ lab pro
I then select File->Export
The jpg image size will then be 8901kB
How to set Lightroom to get the maximum size of the image?
Grateful for answers.

Fredrik

Lightroom classic 12.4 windows 11

[Keith Reeder]

Q1: Why does it matter? JPEG compression algorithms are pretty good, and as long as the physical (H xW) dimensions and image quality are retained, the file size generally isn't important.

Q2: Do you have the "Quality" slider at 100%? 

[Fredrik34154496p9l7]

[SOLVED]
Thanks for your reply. It might not matter, what do I know. I was just wondering what did all the pixels go to?
fredrik

[Keith Reeder]

"Thanks for your reply. It might not matter, what do I know."

Well all I know is that you're a new LightRoom user - but this isn't a LightRoom-specific question, and I imagine you'd rather I didn't make assumptions about your knowledge of what is actually a pretty basic topic of conversation.

[Fredrik34154496p9l7]

That was nice. I wounder how the winter in Ukraine is?

[Conrad_C]

I was just wondering what did all the pixels go to?

By @Fredrik34154496p9l7

The pixels don’t go anywhere, the question is how did JPEG compression change the image? JPEG uses lossy compression, so the more you ask it to compress the file size, the worse the quality looks.

In the animation below is a film scan. Both are exported to JPEG at the full frame dimensions so that every pixel in the scan is there in both. But one was exported at JPEG quality 85 (larger file), and the other was exported at JPEG quality 10 (very small file). As the animation switches between them every 3 seconds, you can see what the difference in quality settings does to the detail in the image to get the file size down. Look at what happens to the detail in the fruit, the skin, and the type on the box.

You want the “maximum size” but if you mean file size, that depends on two things: File format, and the quality you want. If you choose a file format that is lossless (preserves all quality) such as TIFF, PSD, or PNG the maximum size may be very large, maybe too large for fast online viewing but appropriate for a print. If you choose a file format that is lossy such as JPEG, the maximum size can be much smaller, but you must balance the file size with the amount of visual quality reduction of lossy compression.

If you want the academic “maximum size,” save as flat (no layers) TIFF set to no compression. This will produce the mathematically natural file size of the image, based on the number of pixels, number of bits per pixels, and number of channels. This will be a very large data file compared to a JPEG or a digital camera raw file. Therefore, “maximum size” may not be what you actually need, if what you need is a file size appropriate for your delivery purposes.

[DS256]

deleted

[dj_paige]

How to set Lightroom Classic to get the maximum size of the image?

Size of the exported JPG file is usually irrelevant. You are spending time on something that doesn't matter, and can't be precisely controlled, and not worth the time you will spend on it.

The number of pixels in the exported file is what is relevant in this case, and the visual appearance is also relevant. Do not judge exported JPGs by file size.

[DS256]

"I have a B&W negative jpg image of 15228kB
I run this image through Negativ lab pro
I then select File->Export
The jpg image size will then be 8901kB
How to set Lightroom to get the maximum size of the image?"

JPG supports compression which does not affect the number of pixels but the quality.

• In File Explorer, what are the dimesions of pixels when you hove over the 15228kB file
• In a similar light, what are the dimensions for the exported 8901kB file

If there is a difference, then editting done in Negativ Lab Pro changed image.

The difference in size could be caused by the compression selected on the export from Negativ Lab Pro