Suggested settings for downsizing with little loss as possible?

+1.

Don't even consider storing master files online! That's fine for small text documents and office work, but photographs is a whole other animal. It's in a different realm. Use external disks if internal storage is limited.

My own photo archive is now a little over 5 terabytes. I just had to buy a couple of 10TB drives to handle storage and backup for the foreseeable future. As my archive grows, disk capacities grow too, so it works out nicely.

Yes, there's a "cloud" hype going on these days, and you're supposed to store everything online. Those who push that hype need a little reality check.

This is how I work - it may help you.

From the camera I store RAW files, I use Lightroom to develop them (including some initial light capture sharpening) and I keep the RAW files and associated XMP files, which contain the Lightroom adjustments,  on hard disks which are backed up.

To go to Photoshop - I use Lightroom's "Edit in Photoshop" and store the resulting file as a 16 bit PSD. This keeps all the layers , blending etc intact so I can go back an alter later. I may crop - but I do not resize these files (up or down) These are my "Master" files . Again they are stored on hard disk - which is backed up.

So I have both RAW files and PSD masters stored on hard disks and backed up to external hard disks that are removed from the PC after back up.

I do not store master files online - but like everyone else I do post images on-line, post on websites and share images that way.  To do that I go to the Photoshop master PSD file and use Export - Save for Web (legacy) to Export a copy in a format suitable for the web . I select jpeg for photographic images and choose an image size and compression setting as required. In general the pixel size will be smaller than the master and I set the algorithm to Bicubic Sharper.

For printing , again I return to the PSD master, resize to the print output requirements (with resample checked to the required ppi for my printer). Finally I sharpen the image before printing using a bit more aggressive sharpening than looks good on the screen. Then I print.

So to sum up, for photographic images, I have RAW files and master PSDs stored locally without any resizing. Images which are required for online use (not storage) I export a copy as a jpeg (and resize at that export stage).

Dave

5568px by 3712 px, 300 ppi. The 300 ppi is just for print. I'm guessing you want online samples for viewing, but your originals will be on an external drive.

Open your large file and use Image > Duplicate so you do not damage the original file. You will work on a copy.

So for online use, Image > Image Size and let's try 1500 px   Resample and let Automatic do the work for you.

Then File > Export > Save For Web and go with these settings. You should get a decent file size on disk that can be quickly uploaded and viewed.

There is a batch processor that can run this process on all the photos you want to upload and save time, but for now see how this works.

How suggested by JJMack, Lighrroom Photoshop and many other image editing processing applications  have good interpolation methods for resampling images. The other consideration to do is that an interpolation method could work well for some type of images and not for other ones... I think that If you want to reduce image size of different groups of image in the best possible way, you have to try different interpolation method for any groups of images and choose the one that achieve the best result in that particular case...

When you resample an image yoy will always loose some image quality. If you reduce the number of pixels some image details must be discarded. If you increase the number if pixels you need to create details for the image you do no have.   How much quality is lose  depends on the change in the number of pixels.  If you start with a current camera , Phone or tablet these days you are  starting  with 6 to 12 Mega-pixels digital image.  If you need to resample a full frame camera image to fit  on a typical display lets say 1920x1080. Disregarding the crop required  you are resampling a 6 mega-pixels  image to a 2 Mega-pixel image you have 1/3 the number of pixels to store your image's details in.  If the image was high quality in focus, well exposed and developed well from a high quality camera.  Your image will still look good but will have much less fine image details.  Lighrroom Photoshop and many other image editing processing applications  have good interpolation methods for resampling images. In your case you are starting with 20MP and winding up with 2MP. One tenth the amount of pixels.

If you also want to print your images you want to keep your camera files. As well as you web size images.  A 4TB external USB3 dive is under $200 these days. What is 3.3GB less than 10% of that drive capacity. I have not used an internal  computer disk drive in years to store images.