Hi Jeff,
Yes, the same algorithm is used and in addition, users have control over anti-aliasing in the Interpolation dialogue. This is because some subjects like roofs with tiles can produce a strange pattern so an increased level of anti aliasing is required. Too much can soften the image.
Yes, a lot of pixels are lost but the way it is done should be superior in QU. The quality differences are usually less obvious in downsizing the the anti-aliasing can be significant I think.
But a downsized image is not expected to look as good as the original but should be reasonable when viewed at it's smaller on-screen size. The colours of an sRGB image will be subdued when compared to an Adobe RGB or a camera profile image but it is still best to view with a colour management aware application. For Web browsing, Firefox is colour management aware providing the profile is embedded. However, it only seems to work with Adobe RGB and sRGB.
Quality will be lost, not so much from downsizing again but by the fact of re-saving a jpeg. I don't really know how noticeable this will be but 1 extra save should not be significant on such a small image.
Terry
PS.
What exactly do you mean by this?
I wondered too what prompted your questions.
T

This is very important to quality: Quality setting should be 90+ if you are looking for quality. It is the amount of compression vs file size.

Fred

I did a quick web size copy with QU and then conpaired side by side with the orig.  Quite a difference.

The question was prompted by there being a difference in the image quality on local camera club web site when compared with memory of original print or projection at club competitions etc.  There are images on club site by me, QU created and they look a better quality than some by other members.

The club insists on submitted images being 1024 x 768 @ 72dpi (leaving aside the 72dpi) I found out that the WebMaster reduces the 1024 x 768 down to 800 x 600 and resaves, this is to comply with max image size allowed by web hosting site.

I asked why they do not have the images submitted in 800 x 600 and got a blank look, I further pointed out that as far as I am aware it is not good practice to keep resaving jpeg on jpeg and got another blank look.

So I just thought I would ask if QU does a better web quality that other progs. (I don't think the current WebMaster is using PS.)



Just for you to have a laugh I copy below the club instructions for creating a Web size image.


''IMAGE SIZE
TO RESIZE IMAGES FOR DIGITAL PROJECTION IN COMPETITIONS

1. OPEN IMAGE IN PHOTOSHOP Flatten any layers (duplicate if wanted later)

2. From task bar click on IMAGE

3. From drop down menu for MODE check that RGB and 8 Bits Channel are ticked.

4. From same menu click on IMAGE SIZE.
In Image Size box
(a) Make sure that Resample Image is ticked
(b) Change Resolution to 72 p.p.i.
(c) Change largest Pixel Dimensions (may be Width or Height) to 1024 pixels
(d) If the Shorter dimension is now more than 768 change to 768 pixels.
Note: the longer side will now be less than 1024 (this is correct)
Example: With a square format image the end size will be 768 X 768

5. From FILE Select SAVE AS
In Save as Box
(a) File name: Type in the Exact Title you wish to give your entry.
(b) Format: From drop down menu select Jpeg
(c) Save In: (Top of Box) From drop down List choose Location of choice

6. Finally click on SAVE (bottom right of box)

This will save your image to a location (and folder) ready to Email or copy to a Disk for digital projection in the  Digital Competitions.
This leaves your original (photoshop) Image unaltered in its original location, provided you click NO when asked if you wish to save changes to your original image, when closing down.

QUICK METHOD To crop any part of your image down to 1024 X 768 pixels.

1. Open Image in Photoshop

2. Select Crop Tool

3. Change settings on Task Bar to Width 1024 px Height 768 px Resolution 72
Important that you type ‘px’ after the size. (Resolution is default at pixels per Inch)
You can toggle between 1024 for Width or Height in the Task Bar.

4. Crop area of your choice. (it can be as small an area as you wish) and it will always be 1024px X768px and 72ppi.

5. and 6. as above.

Please use the same method and sizes for submissions to the WEB (Web Master will resize down and save for the web). Send by email or disk to the Webmaster:  address and email can be found in the Programme issued to all members.''

Compare that lot with QU method.

Jeff

Good one, Fred, thank you!  I had indeed overlooked this technique, and I'll certainly be able to make use of it in the future.

If my thinking is correct--and I'm basing my thinking on your example--your method DOUBLES the choices in the QI menu when downsizing images...or allows some "fine tuning" of the downsized image dimensions, so to speak.

This is not something to which I've given a great deal of thought.  But I do remember many times making email/web size copies when I just had the vague feeling that I ought to have more choices than were in the drop-down menu.  I was right!  I DO have more choices.

Wow Jeff!  The above sounds like the royal brush off!


... and Owen,
to reply to your thoughts, I would have to say, broadly, yes, you can fine tune your size, but always remember, the aspect ratio (ratio of horizontal to vertical) rules.
In other words, you can file tune one size, and the other side will take care of itself depending on aspect ratio.
By setting both sides the same, you assure yourself that one side will be the the requested size, and the other side will be as big as it can go, constrained my the aspect ratio.

There are two distinct places to use to create e-mail web size copies. That is what you are probably remembering.

 A right click on a thumbnail of a selected image and a click on Make email/web size copies, will provide a somewhat different set of options.

I use this a lot when Terry and I share images and the filters we made.

Hope I didn't muddy the water too much!

Fred

Don't know just what you mean by royal brush off, but then I have spent this morning and half afternoon concreting in a fancy post, wooden/steel post that is, not a forum post.  I am about knackered.

Any way got royal permission to fire up QU and checked tip.

I don't think I have used that method.  If I have well it's craft moments again.

Thanks

Jeff

Jeff,
You have to understand that knackered is not a word we hear on this side of the pond.
Could you, perhaps, put "Knackered" in some sort of level for us.?

Where would it fit; between what numbers?

1) Getting tired

2) Need a break

3) Getting bushed

4) Flagged out

5) Fagged out

6) Exhausted

7) Pooped

Dog tired

9) Need a nap

10) Last time I do one of these!

11) I don't care what it costs. Call the repairman!