A Question

[FrBrGr]

I don't know if this can be answered, because I don't know if anyone can see what I am seeing.

 

With some of Brandy's pics, I am getting (from my point of view) an unwanted effect - Kind of like the images in the pic have been "frosted" or something. If you can see what I see, then this is an example:

 

[image]http://englishfetishangels.com/brandy/29.%20free%20fotos%20coyote%20fun/thumb_002.jpg[/image]

 

. . . while others are sharp and clear, like this one:

 

[image]http://vdsden.thefurden.com/cpgfd/albums/userpics/12433/thumb_002.jpg[/image]

 

Maybe the "frosted" look is for artistic effect, but to me it's distracting and it takes away from the softness of the fur and the woman, which is why I want to know if it's just my computer that sees the pic like this, or do others?

 

TIA . . .

[AKcoyote]

I see the same problem on the first image. It could be a pixelated effect if the image was enlarged from a smaller format.

[FrBrGr]

I wonder if this is what Brandy intends, or if it's something she may want to correct . . . ?

 

Brandy, if you're reading this, what say you?

[Worker 11811]

Compression artifacts.

 

Most people think of JPEG files simply as "pictures" but, in reality, "JPEG" is an acronym for "Joint Photographic Experts Group", the committee of computer scientists who devised this method for broadcasting pictures via computer/internet.

 

The main claim to fame of JPEG images is not simply that they are pictures but that they are COMPRESSED pictures. By encoding a picture as a JPEG instead of some other format, such as a "bitmap" or a "TIFF" (an acronym for "Tagged Image File Format"), you can decrease the size of the file and, therefore, the amount of information that needs to be sent over the internet. This allows us to send more pictures over the wire in less time. A well made JPEG file can be as little as 10% the size of the original with only a little loss of quality!

 

Aha! But, as Shakespeare said, "There's the rub!"

 

In order to get those huge gains in picture compression you have to lower the quality of the resulting image. Every time you turn a picture into a JPEG you are asking your computer to make a trade-off for you: Image quality vs. file size.

 

Aha!!

 

How much are you willing to sacrifice, in terms of quality, to get a file that is small enough to be easy to send over the internet?

 

Those little "speckles" and "checkerboard" effects you see in some pictures are known as "compression artifacts"... The result of the trade-off that the person made in order to send you the picture via the internet. 90% of the time, nobody notices or, if they do, they understand that some images aren't as sharp and clear as others when viewed on computers/internet. Every once in a while, you run into one that has visible artifacts in it. That's what's happening in your picture.

 

The technical reasons for these artifacts have to do with contrast between pixels and the resolution and/or the pixel dimensions of the starting image. It's all rather arcane, really. I don't understand everything about it either. I just know why it happens.

 

Now... There is a second part to this story and I believe it has to do with your web browser.

 

Many web browser application programs have a feature whereby some images embedded in pages are automatically resized to fit your screen. Move your mouse cursor over the image and watch what happens. Does it turn into a little magnifying glass with a "+" sign inside? That means your browser has auto-resized the image for you.

 

This is done as a convenience for you so you won't have to scroll your screen just to read all the text when there is a large image. But, again, this convenience has its trade-offs. Resizing the picture further degrades the image quality, sometimes.

 

Try clicking on the image to see if, when expanded to original size, the compression artifacts go away. If so, you can assume that auto-resize is the culprit.

 

If you don't like what auto-resize does to your pictures you can turn it off in the preferences panel for your browser.

 

By no means am I saying Brandy has sent us a bad picture! No! Her pictures are WAY above average!

 

Basically, what has happened is that we've come across a "Perfect Storm" of circumstances where trade-off upon trade-off, all done for convenience sake, has resulted in an image that doesn't look as good as it can in every circumstance. This is the kind of thing we will have to learn to put up with if we want to use computers to share pictures and other information via the internet.

 

Moral of the story: When somebody says to you, "It's better because it's digital!" you can point to this thread and tell them, "Bullshit!"

 

P.S. Brandy - Try resizing the picture up or down a few pixels so that the dimensions are an even power of two. Better still, an even multiple of 16.

Secondarily, try cutting the contrast just by one or two notches. Do this by adjusting the gamma slider in your "Levels" dialog a few clicks to the right. (To .95 or .90.) or by running the Gaussian blur filter on its smallest setting above zero.

[FrBrGr]

Many web browser application programs have a feature whereby some images embedded in pages are automatically resized to fit your screen. Move your mouse cursor over the image and watch what happens. Does it turn into a little magnifying glass with a "+" sign inside? That means your browser has auto-resized the image for you.

 

This is done as a convenience for you so you won't have to scroll your screen just to read all the text when there is a large image. But, again, this convenience has its trade-offs. Resizing the picture further degrades the image quality, sometimes.

 

Try clicking on the image to see if, when expanded to original size, the compression artifacts go away. If so, you can assume that auto-resize is the culprit.

 

Yes, the pic has been auto-resized, but no, by clicking on the image, the compression artifacts don't go away, so I presume, from your explanation, Worker, that auto-resize is not the culprit.

 

(Wow - I think I'm a technodolt to begin with, and then I read something like your explanation, and I go running to find my duct tape! )

[Worker 11811]

GAFFER'S TAPE!!

 

If you click on the image within the forum message page, it opens up into its own window...

 

But the resulting image is resized too! Hover your mouse over THAT image and see if you get a "magnifying glass" cursor... THEN click on the image. The image should suddenly grow to about twice the size.

 

If THIS image is clear, then you know it's resizing that is the main culprit.

 

[ReFur]

I know hat you mean, FrBrGr!! Sometimes I am shocked I understand what Worker has written!! ...but, he very quickly explains to me, from time-to-time, that I am still clueless!!

[RonGav]

As mentioned earlier, could it be an intended effect --- maybe too much "sharpening" in PhotoShop? Just a thought.

[ReFur]

Ron, Love your new avatar!!

 

Linda

[Worker 11811]

Some of the photos are sharpened but I don't think that's the entire problem in this case.

 

There are areas of pixels, especially in the shoulder and in the specular highlights in the fur where the pixels are almost pure white, surrounded by large areas of dark color. The JPEG format is particularly prone to creating artifacts in situations like that. This is known as "block distortion", sometimes called the "mosquito effect". Using a sharpen filter can increase this effect.

 

Here an example of the "mosquito effect" caused by JPEG artifacts.

[image]http://i107.photobucket.com/albums/m294/Cirrus01/Mosq.jpg[/image]

See how it looks like a swarm of mosquitos flying around the edges of the letters? That's how it got its name.

 

 

Running a Gaussian blur effect on the image will smooth out some of those dark-to-light contrasts and lessen the effect. Adjusting the gamma (contrast) setting of the image will do the same without "de-sharpening" the picture.

 

Also, since the JPEG algorithm divides the picture up into blocks of 2 - 16 pixels before it compresses, sometimes changing the image's pixel dimensions will remove these artifacts (or lessen them) because the computer doesn't have to do so much "filling in" to calculate the final image.

[FrBrGr]

Running a Gaussian blur effect on the image . . . Adjusting the gamma (contrast) setting . . . Also, since the JPEG algorithm divides the picture . . .

 

WHERE'S THE GAFFER'S TAPE (Gaffer's tape - Now that's something I understand! )

 

Thanks, Worker - I'll study this for a week or so and see if I finally get it . . .

[Worker 11811]

Funny gaff tape story:

 

I was in a car accident one evening. Just a fender bender but the other guy's tail light was knocked loose and it was hanging by the wire. The guy was saying, "I can't drive like this! What am I going to do?!" He was beside himself.

 

I reached into the trunk of my car and pulled out my trusty roll of gaff!

 

ZIP!!... ZIP!!... STICK!!... STICK!!... "There you go! Good as new!", I said.

 

The guy's chin was on the pavement! We exchanged insurance cards and he was shaking his head the whole time.

He got back into his car and, just as he was getting ready to drive off I assured him, "Don't worry! It'll hold!"