TheDman Loc: USA

Not at all true.

Notorious T.O.D. Loc: Harrisburg, North Carolina

camerapapi Loc: Miami, Fl.

"However, your jpeg file can vary in size by increasing or decreasing the dpi, a jpeg saved @72dpi will be a lot smaller than the same one saved @300dpi. Cheers!"

I would call it PPI (pixels per inch) and not dpi. Dpi is commonly used when talking about a print resolution.
JPEG images, as has already been discussed, have different sizes depending on the compression used. Sizes are also different at different ppi like it has been already stated by one of the gentlemen that made comments on this thread.

lamiaceae Loc: San Luis Obispo County, CA

That question is a joke, right? You do know what Compressed means? If you want all your information in your final files, save as TIFF files. But then you probably can not email them.

I often make two final versions, one as a TIF and one as a JPG for emailing and Web publishing. I work with RAW files in Photoshop CS6, use 16-bit 300ppi PSD or PSB files for working with my images. Many of my images when they say are Focus Stacks or Stitched Panoramas can be huge files, well over 1.2 GB! Those are best saved for archiving as PDB, but for publishing or really any use, I then make a JPG.

TheDman Loc: USA

And that would be completely erroneous. ppi has no effect on file size.

GoofyNewfie Loc: Kansas City

Other than your correct usage of PPI, this is pure BS!
Read some of the other posts that dispute this and look at mine where I posted the file sizes of the same photo saved at different PPI.
They were EXACTLY the same file size!
PPI has no effect on file size!
Please stop posting erroneous information!!!!!!

burkphoto Loc: High Point, NC

!

Resolution settings in image files are references for page layout programs. They simply tell a page layout program how big to scale the image when it is initially imported onto (placed) on a page.

Pixels do not have dimensions until displayed or printed. They are just numbers. DOTS have dimensions.

Mike59 Loc: New York City

Is a TIFF file larger than a RAW file? I thought the RAW file was, considering that it holds all the information the sensor picked up.

pentaxion Loc: Daytona Beach

Yes, because the TIFF contains the raw information plus the adjustments to it.

burkphoto Loc: High Point, NC

Raw files can be compressed, and so can TIFFs. Depending on compression, one or the other may be the larger...

Apaflo Loc: Anchorage, Alaska

That is not true.

A RAW file is sensor data that is encoded using a Bayor Color Filter Array mosaic. The CFA has a pattern, which is external to the file data, thus allowing vastly more information to be encoded without increasing the in file data.

A TIFF file is an RGB bitmap that necessarilly has to contain within the file all of the information it holds. The TIFF file does not contain any sensor data.

pentaxion Loc: Daytona Beach

OK. I guess what I was thinking is that a TIFF can contain layers in addition to the base file.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

I think you should take a look at this. First image saved at 10 dpi, the second saved at 1200 dpi. One is 1.25 mb and the other is 1.32 mb.

DPI describes printer resolution, dots per inch. PPI describes image resolution - pixels per inch. You cannot change printer resolution by saving the image at 72 dpi or 300 dpi, unless you resample (resize) the image.

https://www.andrewdaceyphotography.com/articles/dpi/
https://99designs.com/blog/tips/ppi-vs-dpi-whats-the-difference/

(Download)

1200 ppi

(Download)

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

First, the raw file never changes as a result of editing. Your edits in Lr are saved in the Lrcat.preview files by default, and you have the option of writing the edits to an .xmp file, which is usually tiny - 9 kb.

Second, when you export the edits to a bit map, if you choose jpeg, the quality setting of the file will determine the file size - an high quality jpeg save at a setting of 12 will be quite large, and will have the least amount of compression, but the same file saved at a quality setting of 7 will be considerably smaller due to greater compression.

https://photographylife.com/jpeg-compression-levels-in-photoshop-and-lightroom

blackest Loc: Ireland

The sensor collects data at pixel sites each has a filter red blue or green this means each pixel site only has one third of the image data for each site when the raw data is converted into colors the data from nearby pixels is used to create values for the other 2 colors. the end result is assuming 14 bits is a 14bit value for red 14bit value for blue a 14 bit value for green. But once these values are calculated there is 3 x as much data per pixel.

So a tiff file will tend to be larger than a raw file, it's also possible to apply lossless compression which will drive down the file size without compromising the data.

In theory there is no reason why a change in dpi should change the file size if the pixels are identical. Are they though? Sharpening and Noise reduction will change the pixel values within a jpeg. Often there is sharpening applied which differs sharpening for screen or for print on export.

It is easily possible that the difference noted in file size is due to a small difference in processing. Unless your OCD is really bad in practice does it matter?