editing images on Mac with PREVIEW

[Bill Gill]

I'm not an expert with this, but I use PREVIEW to size photos for posting here. PREVIEW is the default application on a Mac for image editing. Unless you have deliberately set up another application for editing as your default, it will automatically open in PREVIEW when you click on a thumbnail image.

(I don't know how to mix photos and text within a single post on this forum, so what will follow will be an awkward series of replies, each with a single image and acompanying text. Please bear with me on this, it will take a bit to get them all in)

[Bill Gill]

There are a few ways to open PREVIEW
1. The simplest is click on a photo thumbnail to open it. That's what I do when I want to size a photo for the forum. When you do you should see this at the left end of the toolbar on the top of your screen (See the first, very skinny, toolbar image below.It's just above the PREVIW icon)

2. The DOCK (the bar with the applications you use most often on Mac) has an icon for PREVIEW that looks like a photo of a rocky shore with a magnifying Loupe on part of it. Below is that icon and my DOCK showing the icon -yours probably has applications in a different order. The skinny DOCK image is below the PREVIEW icon)

[Bill Gill]

Click on TOOLS and you get a drop down menu that I can't take a screen shot of.
The fourth choice is ADJUST SIZE. Click on it and you get a drop down menu that shows you the size in pixels and resolution in pixles/inch of your photo.

I make the biggest dimension somewhere around 800 to 1000 pixels for the forum and make the resolution 72 pixels/inch.

At this point the image file size is usually still to big to post here so next step...

[Bill Gill]

... the next step is to go up to the toolbar at the top left of the screen again and click on FILE right next to the word PREVIEW. That opens another drop down menu that I can't take a screen shot of. There is a list of about 15 choices. The one that is relevant is EXPORT.

If you click EXPORT you get yet another drop down menu that lets you rename the image (do give it a new name). I ignore TAGS. The default place to save it is the folder where it came from, in this example that happens to be the desk top. Next shows the format, click on the arrows and select jpg if the file is something else. Then there is a slider to adjust the "Quality" (Resolution) from LEAST to BEST. I keep that under 200KB. I leave ALPHA checked. Under that is FILE SIZE. I make sure it is less than 230 KB for the forum, if it is bigger, I re-adjust the slider.

When all is as I want, I click OK on bottom right and the image closes back to a thumbnail, in this case on my desktop and I can then post that image on the forum where it stays forever, making Russ (and all members) very happy

I know that sounds complicated, but it works and you get used to it after awhile. Hope that helps. If you have questions, please ask and I"ll answer as best I can.

[Bill Gill]

YIPES! I forgot a most important step!!!
NEVER resize your original photo. If you do you will have permanently changed it's size and possibly resolution. First step: Make a copy of your photo and resize it, not your original - keep that original file safe as is.

[nemmrrc]

Thanks for the tutorial.

It is also possible to resize images using Photos on your Mac. Granted, Photos is way more resource intensive than Preview.

Jaime

[Bill Gill]

A quick update for anyone who checks this thread:
Recently I updated the computer operating system to Big Sur and Preview does not work simply
or reliably for resizing photos at this time (February 2021).

After spending hours on the phone with Apple Support, a helpful rep got back to me with a
work around solution that sort of works, usually, but is much too complicated for a simple method
for posting photos on forums. The rep indicated that "Engineering" was looking at the problem, but did not
know when a fix might be available.

Additionally, GIMP (2.10.22) was my other go-to for resizing and editing photos. It does not play well with Big Sur either.
Neither does Inkscape, the vector drawing program.

[finescalerr]

My current photo program, Affinity Photo, is now on sale for $25. It's a bargain at 15 times the price and the equal of Photoshop. You buy it once and own it forever and every update they send makes it better. You can use it accurately to resize images. It is available for PC, Mac, iPad, and probably Android tablets.

I've called AppleCare for help a couple of times for perplexing issues. My experience with "Engineering" is that they are a bunch of nincompoops. Once they told me I was having trouble with some mp3 (music) files because my computer had Photoshop! After about 50 hours of analysis I finally discovered the actual problem was a change in Apple's operating system that no longer recognized a particular mp3 coding. That really ticked me off because whether rtf, tiff, dwg, txt, or mp3, all are supposed to work on all devices regardless of coding or operating system. But that's Apple: Arrogant, unhelpful and, unless they can make money from it, even incompetent.

Yes, I still own a lot of Apple products but I really dislike the corporation's attitude. And, if I have a software problem, I've learned I'd better figure out how to solve it myself.

Russ