Jagged edges, what's happening here?

[Paz]

If I save this picture in Photoshop I get these jagged edges.
I have seen this before on other images I got from the web.
Can anybody tell me what is happening here?

Attached files are: the original image, the image cropped in Picasa (looks fine), and the image cropped in Photoshop with the strange jagged edges (see bird or hair).

 

[Steve]

I'm not seeing any difference in my browser zoomed to 400%
I've opened 1 and 3 in PS and don't see a difference there either.

 

[Paz]

You don't see this:




?

 

[Paz]

Thanks for at least trying to help.
But if you still can't see a difference, could you maybe save the first file (the original) in your version of Photoshop, and post it here?
I tried in Photoshop CS4 & CS5, but I get the same result.

 

[SeniorS]

When you saving croped image at PS what Quality you set? That's happened to bird with Quality=5.


For best result save with Quality 12.
And still some jagged edges can apear. Much less,almost unvisible but it can because of jpg compresion. And more times you open and resave it (with some changes done to image) more it will apear.
So best option if you want to work with jpg, save it as tif with LZH compresion (smaller size) and when all work is done save it to jpg with maximum quality.

 

[Paz]

I usually save with quality 11, because the difference is so small.
But even when I save it as tif or png, I get the same jagged edges.
Don't you get the same? If not, could you please show me?
The jpg artifacts aren't as bad as they seem if you open the attached images.

 

[SeniorS]

Here is resaved (Q=12):

 

[SeniorS]

I took a look on those at 500%.
Mine resaved copy was almost exactly as origin. Same jagged edges or sharp edges. Picasa's image looks little bluried that original itself. So that's picasa probably is using some own algoritm for saving jpg.

 

[Paz]

Thank you. You've got the same thing happening I see (do you too?).
Why is this only happening in Photoshop, and not in Picasa or even Paint for example?
It obviously is not happening to all images, but even so, how is it possible that a free program (Picasa) and a crappy program (Paint) are able to handle this image perfectly fine, and an expensive program like Photoshop isn't?
Can you or anybody else figure out what Photoshop is doing differently?

 

[SeniorS]

You get it wrong. Photoshop is doing perfectly what it have to do. What you give to it you get back exact the same.
Compare your original file (not resaved) with Picasa. They are diferent.
Original have crisp, sharp edges. Picasa's less sharp. Resaved one is identical to original!!!
This time you like how picasa changed your image. But maybe with other that would be diferent.

If you want to remove that sharp edges you can try one trick. Remember image width, resize image to 120% then resize back to origanl width.
That will lower "jagged" edges a little.

 

[Paz]

Sorry, I didn't see your second to last reply before I posted mine.
But your resaved copy wasn't like the original at all.
Something is definitely wrong.
If you look at the images (original and your resaved one) with Windows Photo Viewer in fullscreen (slide show, F11) on a screen of at least 1200 pixels high, you would clearly see what's wrong with it.
If you do not, can anybody else try it too? So I know it's not just me.
Because I have also tried it on my father's Mac, and the difference is very clear. Between original and a Photoshop saved copy as png, tif or whatever other format you would like to try.
SeniorS, I've attached two more screenshots, your resaved one and the original; isn't the difference very clear (when opened)?
Once again, if not, could somebody else confirm?

 

[Paz]

Please click to open in fullscreen

 

[Steve]

If you're referring to this:


No, I'm not seeing any difference

Photoshop is doing perfectly what it have to do. What you give to it you get back exact the same.
...................... Picasa's less sharp

It's a 605px X 600px image, resolution 72, very small.

 

[SeniorS]

Okey, i can see that now. That's something new.
Other programs but PS shows that jagged edges. Still in PS they ar normal. I assumu something with ... i don't know.

Steve: Problem is that windows photo viewer, google chrome etc. shows those jagged edges not PS. Very intresting.



P.S. I'm too tired to think why it happens. I'll check tomorrow at work's computer with PS3 (XP).

Quick idea: By the way...you using windows 7? Me too. Probably that is windows system codec (jpg decriptor or something) problem.

 

[Paz]

Steve, that is indeed what I'm referring to. I'll agree that you have to go fullscreen to really notice it. But if you do, it's very apparent.

SeniorS, I do use Windows 7. But as I said, your saved copy looks exactly the same as mine on a Mac or iPad. So with the rough jagged edges.
I have asked others too, and they saw the same toothed lines as I did on the Photoshop saved ones.
Somebody (cropped and) saved the image in IrfanView, and that one too looks fine too.
So it really is just Photoshop that is doing something in a different way compared to all other programs.
Now we'll just have to find out what that is, so we (or maybe just I) can prevent it from happening...

 

[SeniorS]

Okey, last attempt today

Let's think logical.
1. PS is good and don't mess with images usually, what there is in file it shows at it is.
2. Original and resaved opened in PS are identical.
3. Original and resaved opened elsewhere looks diferent.
4. Resaved opened elsewhere looks like in PS.
5. Original opened elsewhere looks diferent than in PS.

Conclusion: natural question is from what source you get original file?
And i'm not sotware designer ang coder.

So question to them: about diferent jpg algoritms? Is that possible that two programms in some case reads one file jpg diferent.

 

[Paz]

By all means, go to bed if you're tired! I can wait another day!
The original is from the official site of the label.
Although I don't think that particular site is still around.

I'm going to try and save that image in Photoshop on a Mac, see what that does.
And then I'll see you tomorrow!

 

[Paz]

Well, the same thing happens on a Mac. Whether saved as jpg or png (as you can see from the screenshot, I uploaded the latter), jagged edges appear once the image is saved in Photoshop. It looks the same when viewed in a browser or in Preview.

 

[Vafann]

I have been able to see the jagged edges you are talking about from the beginning without having to enlarge the picture. I have read somewhere that it can have something to do with aliasing and anti-aliasing, and the resolution of the picture. Also sharpening. I remember something about that the picture might look jagged on the screen, but will print out perfectly.

Anyway, I found this for you, maybe theres is something here that will trigger some kind of "AHA!" moment, like maybe the bicubic thing with it being set to "nearest neighbor" or something?

Resize Images Correctly using photoshop | Simply PSD Photoshop Tutorials

 

[SeniorS]

Okey, round two and final.

I dig it to the point that jpg was created by something call "gd-jpeg v1.0" (open file in notepad, there's at begining usually are some intresting information).

It "is an open source code library for the dynamic creation of images by programmers.". Mostly used for web and, as we know, jpg designed for human eye, so must been those combined together to show more smooth edges. I didn't find any specific information about how it's done.

At phisical level original and resaved seems equal. I tried to resave it as tif and view with windows picture viewer it had those jagged lines too and there is no way that tif are worse than jpeg. So it's some "cheating" done by viewer.

For diging in more asks for deeper research for specific algoritm etc. than i'll ever needed. It is really intresting but not worth spending too much time to it.

If you really want to understand what and why it happens try ask that question on some specific (there that word again) forums about jpeg formats, web programing ...who actually works with them, building own encriptor, decriptor, generating thumnails and things like that. There is some of them, i believe. They could (if they want) to explain things.

Of course, may be there is some superguru who sleeps now.

My resume for that is, it is how it is and nothing can't be changed. At least not with PS. Maybe there is some GD converter/resaver available.


I've been spoken