EOS Rebel T7 Does changing resolution affect existing photos on the memory card?

[McLeanToInspire]

Hi I need to know if changing the resolution setting on my Canon eos t7 to a higher resolution changes the photos I've already taken kn the sd card currently in the camera or if it only changes the resolution of the ones I take from the time I changed the setting onwards??  Also is there a way to increase the resolution of the images( for free) after I've already taken them for photos I did not increase the resolution before taking? I'm newer to photography and just realized my camera setting was set to medium grade for the photos and I didn't understand why my photos were saying they were not high enough resolution for certain printing projects now that I've started a photography business. I have over 40,000 photos that were taken over the years and were taken at these lower resolutions that I now need to see how to fix ones I'm trying to sell that need to be a higher resolution for certain print projects to make them higher resolution. I am newer tp this so if someone can explain it in simpler terms I would appreciate it were self taught and have been having to learn a huge range of things in a small amount of time. Thank you 

[rs-eos]

No.   All prior photos would be in the same resolution as when there were initially captured.

While there is software now that can do a decent job at upscaling images, they will indeed have limits and can lead to poor results.

Personally, I would reshoot the images that you want to attempt to sell.   Beyond just resolution, I'm sure you've learned over the years more about composition and all the other numerous aspects of photography that make for better images.

[McLeanToInspire]

If the photos are primarily nature, landscape and wildlife,sunsets ect..things I cant recreate theres no way Ican go about reshooting those then. Or is there something else you meant by that? Like re- photographing the photo itself? 

or if we paid for a software like photoshop instead of a free software would it be capable of actually increasing the resolution?

I got samples of our photos printed from the company we chose and they turned out very clear and high quality so I thought nothing of it until I went to use a different company for printing some producta the first company did not offer I was looking to put some of the photos we have on a throw blanket and then one of the companies was saying the photos were not high enough resolution but the 2nd blanket printing company did not say that nor the professional print lab we used for our prints and metal art So I'm trying to see about how to handle the resolution before I ordered samples of the blanket products.

 I do have my photos backed up on a cloud and my computer both. But keep the SD cards also just in case. We back up my photos after each shoot/day usually. 

[kvbarkley]

"If the photos are primarily nature, landscape and wildlife,sunsets ect..things I cant recreate theres no way Ican go about reshooting those then."

Actually, these are the kinds of photos you *can* recreate. Look at all the folks who do exact copies of Ansel Adams images. While it might be expensive, and you might not get the exact same moose, you should be able to reshoot similar images. It is weddings and other family events that are impossible to re-shoot!

[rs-eos]

Also, hoping you don't have all your photos only on SD cards and that you've backed them up to either a computer or cloud service.

[kvbarkley]

https://www.lensrentals.com/blog/2023/10/does-recent-advancements-in-upscaling-make-the-megapixel-ra...

Has some info on up-rezzing software, but these programs need a lot to work with , if you shot in 1080x640, there is little hope.

[ebiggs1]

Here is why. All camera always shoot at the highest resolution they can. The size reduction comes when you save that image to SD. The camera deletes and discards data that it doesn't deem as necessary to get to the size setting you select. Since data is no longer there it can't be put back in.

The resampling software basically does the opposite it guesses on what would work and creates data. Depending on, again, your settings resampling doubles the pixels in the image. The software sees a red pixel for instance in the photo. It thinks another red pixel would look really good there so it creates one and adds it to the image. Sometimes this works but sometimes the pixel next to that red one was black or some other color so the result is less than perfect.

You didn't indicate what size or type print you are trying to make. If the size is less than 8x10, say 5x7, you may have all the resolution you need as is.

[BurnUnit]

Just thinking out loud here. But printing even a higher resolution photo on a blanket is not going to produce the sharpness or detail of the same shot on conventional photo paper. And that should be understandable and perfectly acceptable for a blanket.

What are the pixel dimensions of the images in question, and what is the size of the printed area on the blanket?

[johnrmoyer]

My advice is to always set the camera to save a raw file, then the free Canon DPP software can process it on a computer. Since it is too late for that, here are some less desirable possibilities. (Others have suggested AI upscaling software that one pays to use, but I prefer free software.) The free to download Canon DPP software will also upscale photos, but my example in this post started with a raw file from the camera and not a JPEG. There are many free software programs that will scale an image using various algorithms.

Examples are included in this post. The caption tells how the image was processed. I expect it will be necessary to view the images full screen to see the differences.

GraphicsMagick is free software and has a good algorithm for increasing the number of pixels. 200% works reasonably well when followed by unsharp mask. The default algorithm is described at https://en.wikipedia.org/wiki/Lanczos_algorithm in case you might like a little mathematics. Gimp free software with the GMIC plugin has 3 or 4 up scale algorithms.

The graphics magic command line:

gm convert -verbose IMG_3476c.JPG -resize "200%" -unsharp 0x1 -define 'jpeg:dct-method=float,jpeg:optimize-coding=true' -interlace line  -quality 93 IMG_3476x2.JPG

The DCCI algorithm is described at: https://en.wikipedia.org/wiki/Directional_Cubic_Convolution_Interpolation

crop from original image processed with free to download Canon DPP

crop from same image scaled 200% using graphicsmagick free software

crop from same image using GMIC plugin for gimp free software and DCCI 2x algorithm

scaled to 200% using free to download Canon DPP software (I started with raw file and not JPEG)