Changing photo size question

I think this may be a good place to post. I'm seeing some photos that are posting physically larger (not mb wise, just larger image on screen). I wanted to try the same for the weekly thread, but not seeing how just yet. I did a couple of searches and cruised some through the development threads, but maybe someone can point me in a better direction? I could swear I saw a post at some point about it. Apologies if this fits better somewhere else on the forum. Thank you.

-Matt

How to upload your own pictures to this site.

Thank you for the feedback. I think I'm just confusing resize/download/upload in general. I saw a post in the weekly thread and thought there might be a way to post a larger physical rendering. I'm copy/pasting here the one that I'm referring to for example only. I know there is the 4.0 mb limit, but thought for a moment we could have it show larger in the thread. That part is likely me not fully understanding downloading a down sized sample from Apple Photos to then upload here. There is no option to choose mb size. Only width, height, or dimension are available when choosing a size other than small, medium, large, or full size in Apple Photos. Need to investigate further (and maybe use Raw Photo or Pixelmator direct) to download instead of Apple Photos. I always just did full size for dpreview.

I think what you'll want to look for is JPG quality or JPG Compression or something similar. You can upload large (20mpx) images if you save as something less than the highest quality JPG. Try it with your own software to see how it works. The picture will still look fine, even when viewed at 100%.

Since the @Meeces mentioned Apple Photos,

In Apple Photos on macOS, File, Export, JPEG, size, quality.

The size of the image file may be reduced by reducing the size in pixels, which is not what was wanted but may be necessary to get a smaller file.
The size of the image file may be reduced by reducing the JPEG quality. Some decades ago when the JPEG standard was created, quality went from 10 to 100. Apple photos has 4 choices for quality, but does not give the quality numbers. JPEG compression trades file size for image quality and a lower quality will yield a smaller file size. The lowest quality will tend to posterize the image with sudden instead of gradual changes in color which is especially visible in blue sky.

Useful tutorials on resizing:
www.cambridgeincolour.com/tutorials/image-interpolation.htm
www.cambridgeincolour.com/tutorials/image-resize-for-web.htm

I have used macPorts to install GraphicsMagick on my iMac and have been using it for a long time on my Linux machines. GraphicsMagick gives one more control over the JPEG compression. Improving the color sampling during compression increases the calculation time but does not increase the image file size. For example this command line made an image small enough to post:
/opt/local/bin/gm convert -verbose IMG_3476c.JPG -define 'jpeg:dct-method=float,jpeg:optimize-coding=true' -interlace line -quality 90 IMG_3476cs2.JPG
The image is 4500x3000 pixels. With a quality of 91, the file was still too large. I used the most calculation intensive method for sampling the colors. The image meta data including IPTC and copyright and description seems to me to NOT be preserved by dprevived except when one selects "open" from the image view.

exiftool -G0:2 -a -imagesize -datetimeoriginal -description IMG_3476*.JPG
======== IMG_3476c.JPG
[Composite:Image] Image Size : 4500x3000
[EXIF:Time] Date/Time Original : 2023:03:21 17:04:36
[XMP:Image] Description : Northern Cardinal (Cardinalis cardinalis) in Norman, Oklahoma, United States on March 21, 2023
======== IMG_3476cs2.JPG
[Composite:Image] Image Size : 4500x3000
[EXIF:Time] Date/Time Original : 2023:03:21 17:04:36
[XMP:Image] Description : Northern Cardinal (Cardinalis cardinalis) in Norman, Oklahoma, United States on March 21, 2023
2 image files read

On the Mac I generally do my resizing/compression directly from Photos — provided the original image is part of my Photo Library. Otherwise I use the “built-in” Preview utility. I also have a couple of automation shortcuts to downsize photos from the Finder using the contextual menu.

On iOS I primarily use Image Size. I’ve recently started using CropSize to increase the compression of images (smaller file size) while keeping the original resolution. Images from the Photo Library can be sent directly to either app via the Share Sheet, then saved back to the Library, into a folder, or sent along to another app.

I’m (still) searching for an app that provides a “fit within this box maintaining orientation” option — i.e. No wider than 1600 px, No taller than 1000 px (regardless of image orientation — so "long side/short side variables don't work.) CropSize comes close but pads the extra space with gray — not what I want here. (Note: I’ve just downloaded an update so I might have a pleasant surprise waiting.) Any leads are appreciated.

GraphicsMagick resize will allow you to maintain aspect ratio while specifying height or width in pixels, or almost anything you might want.

This fragment of a shell script is passed a filename and creates a thumbnail that fits in a box of specified size and appends some html to display it to index.html. It also creates a white background and removes the metadata, but that could be skipped.

make_one_thumbnail() {
gm convert -verbose -define jpeg:size=320x240 $1.JPG +profile "*" \
-thumbnail '160x160>' -background white -gravity center \
-extent 160x160 thumbnails/$1.JPG
cat >> index.html << EOF

<div class="thumb">
<a href="${1}.html">
<img src="thumbnails/${1}.JPG" alt="thumbnbail" width=160 height=160>
</a>
<p>
<a href="${1}.html">
${1}</a>
</p></div>

EOF
}

export make_one_thumbnail

Thanks for the additional info. I think I'll stick with just inserting the image as nightowl mentioned. Apple is indeed a bit behind in terms of options for download out of Photos. If I export direct out of RAW Power (not as the plug in for Photos), that gives a lot more options, so I may try that in the future.