Image Dimensions/Resolution dropping after export

[shantanub23289183]

I usually click images in both RAW (Canon) and JPEG format, which I started processing using Lightroom classic recently. One thing I observed is when I export the image after processing, lightroom reduces the dimensions of the image. What I mean is, the image (JPEG) captured by the camera has dimensions of 4160x2768 pixels at 72 dpi. But the image or jpeg exported by lightroom has 3120x2080 pixels only on the same dpi. I have not cropped the image. Also, the export settings are as following:

• Image format: JPEG
• Quality: 100
• Color space: sRGB
• Resize to fit: Unchecked (I even tried with checked and percentage set to 100)
• Resolution: tried with 72 to 300

I am not sure why the dimensions of exported images are lower at this point. Can someone please explain what is happening and how can I get full resolution image without manually giving dimensions in Image Sizing?

Thank you,

[Per Berntsen]

With the image selected in Library, what pixel dimensions does LR report?

[richardplondon]

"Quality" does not affect the number of pixels in the output, nor do "Colorspace" or "Resolution" (ppi).

If Resize is unchecked you should get the native as-imported pixel count being exported (as adjusted and as cropped), regardless of what PPI resolution is attached to that.

Besides the main Crop / Straighten tool, different adjustments can further reduce the count of pixels coming through from the imported file: if you use the Upright tools / the manual Transform tools to adjust perspective, and Constrain Crop is active.

One other question to consider: where are you exporting to? If exporting directly to, or uploading to (for example) a social media or web gallery service, especially a free one, some systems will auto-downsize images that exceed certain pixel dimensions. Even if you then opt to view what that system describes as the "Original" version of that photo. If exporting to your local computer drive, that will not of course be a factor. 

[DS256]

I believe 'Resolution' is only relevant when your output size is in a external size measurement like inches or cm's. I've always wondered why it's always presented as option for all sizing choices.

[richardplondon]

Sometimes a particular Resolution figure is specified by the recipient, who you will be sending the image to. Sometimes their own software workflow might treat an image differently, depending on the PPI number, even though it consists of the same number of pixels. And they don't want to have to change that PPI themselves, before using your image.

Even if it is not affecting that number of pixels that will be included - nor the end usage - and even if you are not Resizing the image in any terms - still LR has got to set some PPI number that the output should be labelled with. That is a compulsory part of the image format. It cannot be left "blank" regardless how little interested anyone may be in this - for example, when the image is purely destined for viewing on screen. 

[Per Berntsen]

Ppi is optional metadata, so Adobe could have included an option to not include it, but they didn't, possibly to keep things simple. After all, it's not a big deal.

Interestingly enough, entering 0 in the resolution field results in a ppi of 300, and leaving the field empty results in 240.

Photoshop's Save for web will strip out the ppi value, provided that Metadata is set to anything but All.

Photoshop's Export will always strip out the ppi value.

Some applications, like ACDSee, will not assign a ppi value when opening an image without ppi.

Photoshop assigns 72 ppi when opening images without a ppi value, to be able to display rulers in inches and centimeters, and also to display type correctly. The value of 72 is chosen arbitrarily, but i has to assign something.

[DS256]

I just re-read your question and realized I didn't pick everything up you were discussing.

• When you load the RAW+JPG are you importing the JPG as a separate file or sidecar?
• What are the dimensions of the RAW file? I assume the dimension of the JPG is 4160x2768 
• What do you mean "I even tried with checked and percentage set to 100". There is no % option on the Image Sizing tab of Export.

I think the confusion is what you may see in the file properties (Explorer or Finder). In Explorer (Windows) both pixel size and DPI are dislay which is confusing (at least I found it). So, I did a test.

I took an original 4928x3264 RAW file and exported it from LR as JPG 3 times.

• The original size and I specfied the Resolution 111
• Reduce to 2000x1325 pixels with a Resolutuion of 112
• Reduced to 800x539 with a Resolution of 113

The result is that each had the correct pixels in the image and DPI was what I set the resolution at as seen in Windows Explorer.

These values correspond to EXIF metadata tags. When I examine the EXIF metadata for these exported file the XResolution/YResolution values are what the Export Resolution was. The ResolutionUnit is 'Inches'.

Confused? That happens with metadata. They are used for more than one purpose.

My research shows that the related EXIF tags are primarily used to store scanner DPI information.

Here's a link to an article which indicates these fields are not used https://www.media.mit.edu/pia/Research/deepview/exif.html.

So, still to the pixel sizes that will be used for printing. Resolution in Export are only when you specify the print size in the Image size from what I've been told.

So, DPI refers to 'Dots Per Inch' for printing. The equivlent for displays is PPI or 'Pixels Per Inch'.

[DS256]

As a comparison, I scanned some slides. The information shown in Windows and the EXIF are shown in the following. The scanner name would normally be shown for 'Make' but I overrode it with the camera that I used.

[Per Berntsen]

When I examine the EXIF metadata for these exported file the XResolution/YResolution values are what the Export Resolution was. The ResolutionUnit is 'Inches'.
Confused? That happens with metadata. They are used for more than one purpose.
My research shows that the related EXIF tags are primarily used to store scanner DPI information.

 "Inches" no doubt means Pixels Per Inch, or PPI, regardless of whether the image was scanned, or produced by a digital camera. If the unit is pixels per centimeter, it will be labelled "Centimeters".

If the image was scanned, a value of for instance 2400 means that the scanner sampled 2400 pixels for one inch of film.

With 4 x 5" film, this will result in an image measuring 9600 x 12000 pixels.

We can use these numbers to calculate the print size at any given PPI. For instance, at 200 PPI, the image would print at 48 x 60 inches. (9600/200 = 48 and 12000/200 =60) The same math applies to images from digital cameras.

Windows wrongly reports PPI as DPI.

DPI (Dots Per Inch) is used for printer resolution – how many ink dots the printer can put down on one inch of paper.

The correct term for both image and scanner resolution is PPI.

[Bob Somrak · Accepted solution]

Here is the file specs for the Canon RP although you have never said which camers you are using.  Depending on what camera you are using the specs may be similar.  Are you sure you are not shooting at S1 and think you are shooting at M1 JPG files.  The sizes match your description

EDIT.  I forgot to attach the specs

[shantanub23289183]

Thank you everyone for providing possible reasons. I was shooting in M Raw + M Jpeg which should have resulted in a similar resolution for raw and jpeg. But after checking raw image size as suggested in one of the responses, I saw the resolutions were lower. One thing I did immediately is checking it again and it produced the same results. But after doing a firmware update (which was pending for a long time and I tried a beta toolkit on the camera), the issue got resolved. It had nothing to do with lightroom export but was due to how the images were captured (should have cross-checked that). But thank you everyone for responding and helping out.