Does reducing a jpg soften it?

Pippan wrote in post #18525586
What software would you recommend? Are saying it's better to uncheck the resample box, as OneLook asked?

Here is some good info:
https://www.webdesigne​rdepot.com/2010/02/the​-myth-of-dpi/

Check this site. It gives a nice explanation of viewing and uploading images
https://www.webdesigne​rdepot.com/2010/02/the​-myth-of-dpi/

OhLook wrote in post #18525611
Yes. How many px/in can I ask for before reaching the point of no return? That is, what resolution does the Web support?

Unless you're preparing an image for print, just forget about ppi. It has nothing to do with image quality as viewed on screen. Nothing.

OhLook wrote in post #18525686
Before any reduction I perform, an image 4000 x 3000 px, copied from ImageBrowser to the desktop, is displayed at about 9 3/8" x 7". Vertical image, 3000 x 4000 px, about 5" x 7".

Forget inches. Inches are relevant only to pieces of paper (or pieces of metal or whatever print medium). The ONLY dimensions relevant to on-screen image quality are pixel dimensions. 4000 x 3000 px is too large for the majority of screens. About 40% of that size is pretty good for most online purposes. Forget pixels per inch because, remember, inches are relevant only to print dimensions.

Oh, as long as your JPEGs don't exceed 10MB, there is no need for you to resize them. AMASS does that for you automatically.

Peano wrote in post #18525737
Forget inches. Inches are relevant only to pieces of paper (or pieces of metal or whatever print medium). The ONLY dimensions relevant to on-screen image quality are pixel dimensions. 4000 x 3000 px is too large for the majority of screens. About 40% of that size is pretty good for most online purposes. Forget pixels per inch because, remember, inches are relevant only to print dimensions.

Gotcha. Thanks. I reported measurements in response to BigAl007's statement about displaying at 200%.

rrblint wrote in post #18525738
Oh, as long as your JPEGs don't exceed 10MB, there is no need for you to resize them. AMASS does that for you automatically.

I'll test that now. SOOC, 2980 x 3827 px. It has disadvantages. The upload takes much longer. Backing up will also take much longer.

Let's see whether AMASS's reducing software is more like mine (ugh) or more like Dave3222's (yay).

OhLook wrote in post #18525742
Gotcha. Thanks. I reported measurements in response to BigAl007's statement about displaying at 200%.

I'll test that now. SOOC, 2980 x 3827 px. It has disadvantages. The upload takes much longer. Backing up will also take much longer.

Let's see whether AMASS's reducing software is more like mine (ugh) or more like Dave3222's (yay).

Hosted photo: posted by OhLook in
./showthread.php?p=185​25742&i=i191831765
forum: RAW, Post Processing & Printing

Looks pretty good to me. The longer upload time is because it's uploading all those details that you want. Same with storage. You have to give some to get some in return.

So I'm clear (because like OhLook, I've been wondering why my uploads don't look sharp like those of, say, Pondrader), the best results will come from uploading a quite large (but less than 10Mb) image and letting AMASS software deal with it? And it's best to leave the resampling box unchecked?

Pippan wrote in post #18525762
So I'm clear (because like OhLook, I've been wondering why my uploads don't look sharp like those of, say, Pondrader), the best results will come from uploading a quite large (but less than 10Mb) image and letting AMASS software deal with it? And it's best to leave the resampling box unchecked?

Yes. If your photo exceeds 10MB then reduce(without resampling) it to 3000 pixels on the long side, not all the way to 1280.

Will delegating the reduction to POTN burden Pekka's server with a lot of extra work? I don't like to impose, generally.

Pippan wrote in post #18525762
So I'm clear (because like OhLook, I've been wondering why my uploads don't look sharp like those of, say, Pondrader), the best results will come from uploading a quite large (but less than 10Mb) image and letting AMASS software deal with it? And it's best to leave the resampling box unchecked?

It seems that what program you use for resizing makes a big difference. Dave3222 didn't say what he used, but it sure got a better result than Preview.

Yes, I've been using Preview too. Might have to take the trouble of going into Photoshop for improvements.

OhLook wrote in post #18525803
Will delegating the reduction to POTN burden Pekka's server with a lot of extra work? I don't like to impose, generally.
It seems that what program you use for resizing makes a big difference. Dave3222 didn't say what he used, but it sure got a better result than Preview.

I apologize. I used Photoshop.

OhLook wrote in post #18525426
Before I saved the PPed image, the vertical grooves on the mailboxes were distinct. After saving, they were muddy. Below, at the right is a detail, SOOC with almost no reduction. At the left is the same bit from the image as posted above, enlarged to the same size. Too much is lost.

Hosted photo: posted by OhLook in
./showthread.php?p=185​25426&i=i21878345
forum: RAW, Post Processing & Printing

OhLook, you have blown up a small, downsized image to match the dimensions of the high res file. Of course this will result in a heavily pixelated image! You're comparing apples to oranges here.

OhLook wrote in post #18525686
I can enlarge images to 100% with a keyboard command and see only parts of them at once, but there's rarely a reason to do so.

Noise reduction and sharpening should be done at 100% size. It's the only way to see the effect properly.

rrblint wrote in post #18525738
Oh, as long as your JPEGs don't exceed 10MB, there is no need for you to resize them. AMASS does that for you automatically.

OhLook wrote in post #18525803
Will delegating the reduction to POTN burden Pekka's server with a lot of extra work? I don't like to impose, generally.

A few months ago I was talking to Pekka (offline) about sharpening algorithms and I did some tests and found that the current POTN algorithms for downsizing and sharpening yield a slightly softer image than when I downsize and sharpen my images myself. So if you think your images are not sharp enough, don't let AMASS resize them for you but upload them in the size you want to display them.

What has not been mentioned (I think) is that downsizing an image softens the edges in that image some indeed. Regardless of format (jpeg, tiff, psd, etc.). Which is why it is recommended to always apply some additional sharpening after downsizing your images. Look at this sample image (it was a test shot for the WWPW thread ). I took it to Photoshop, applied sharpening and then downsized the image to 1024px on the long end. The first version I applied additional sharpening to after resampling it (I ran a High Pass in PS), the second version was not sharpened after resampling it. The image is otherwise unprocessed. The difference is rather subtle but very noticeable.

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Why are you resizing your images at all?

saea501 wrote in post #18525937
Why are you resizing your images at all?

1. Because you don't want large, high res files on the internet where everyone can grab them
2. Because forums such as POTN have limits (both size and MBs)