As others have said, DPI/PPI is metadata. You can edit it in the metadata tab under the Exif section. Make sure the metadata copy mode is set to “Apply modifications”.
The information in the Crop tool is just a guide to show you the maximum size you can display/print the image and still maintain at least the specified PPI, given the resolution of the cropped image.
From RawPedia:
The PPI value (pixels per inch) does not change any physical property of the image, it only serves to help you see what physical size the current crop would print at using that PPI value.
The DPI/PPI is merely a suggestion of how large to display/print the image. If you are specifying the size of the print, the PPI in the metadata is meaningless.
Hi @Lawrence37, as maybe incompletely mentioned in my posting, the X and Y resolution is no longer carried over. Until version 5.9-218 it was always 300 in my JPEGS, from version 5.9-452 it always has the default of 72 …
That is an old dev version. Have you tried 5.10 or a recent development build? The screenshot I posted is of 5.10 and the metadata tags are saved correctly in the exported image.
In RT 5.10 I have a file with this resolution settings
In the JPEG the resolution is missing, leading to the windows default assumption in this specific case of 96 DPI
And here the header of the PP3
I don’t see that it is correctly saved in the output. I would assume due to “copy unchanged” that the X and Y resolution is copied from the raw to the jpeg.
Which might be a good enough reason for a busy shop wanting to streamline workflow or a paper of some sort that are including work from many sources and individuals.
Which is a good reason. You’re basically placing part of your order by setting that metadata.
So yes resolution in digital files is only about communicating intended output size. Communicating such info is an important part of some publishing workflows.
I’ve never been clear about the use case for messing with ppi values, because I don’t normally print and have never used a print shop.
So, I had a “chat” with GPT. After a misunderstanding or two, it said that it is more common for a photographer to set a “normal” (150, 300, 600, na-ni-na) ppi appropriate to the required print medium and to resize the pixel dimensions accordingly …
… rather than keeping the pixel dimensions as-are (except for cropping to the desired aspect ratio) and adjusting the ppi accordingly.
Which usage is favorite with the printing cognoscenti here?
As @nosle and me have mentioned, if the intent is to communicate a certain possible print quality then setting the ppi accordingly is good.
The more so when many images and maybe different source materials (cameras, scans, etc) are involved.
If I just want to print something I do a rough estimate in my head from the pixel numbers and decide if anything needs changing. Usually the data is more than good enough, even 100ppi on the final output can rarely be distinguished from anything with more resolution.
In practical usage I have neither looked at ppi settings or have resized images for print for a really long time. But then most stuff gets prepared for web anyway and there I have predefined actions that take an image and resize and sharpen to a specific pixel size.
Yes, I know that ppi for web does not really matter.
That part was an aside, I should have made that clear.
The gist: I can not remember the last time I had to set ppi on a file for printing.
It’s been more than a while. I also can not remember when I resized, up- or downscaled a file for printing. Output from software is excellent, images are detailed, filesizes are small compared to whatever media one uses to transfer. sRGB JPG 90%, thank you.
Now … that of course excludes custom printing with fine tuned images, custom profiles, manual selection of print media, proof prints, test prints, more test prints, thoughts about framing and so on.
In that league I have never met a lab-technician or print-master that would talk about ppi. They would just ask “That’s the best file you got? Sure? SURE? … Okay, how do you want that print? We can do anything from stamp to skyscraper.”
When placing hundreds of images in dtp software it really helps if the image has DPI info set. You avoid scaling the image by mistake and you get instant and visual feedback on the intentions of the person providing the images. Should it be full bleed or a small thumbnail. Calculating resolution on these hundreds of images while placing them isn’t feasible.
Now I’d you’re the ad and the designer with full access to original files and with full technical and creative control it’s not important but in many cases there are long chains of people involved and it may me more about executing someone else’s decisions. Then dpi is very useful.
