Can you tell the difference?

Here are three images, all the same size, all jpg files. One is saved at the 'highest setting', one at a 'low setting', and one at a 'medium setting'. The primary reason for choosing a lower setting is to allow the images to load faster and reduce the number of bytes transferred over time.

Image "A"

Image "B"

Image "C"

Can you tell which is which?

[This message has been edited by Rod Watson (edited 12-02-99).]

"C" looks good. "A" and "B" aren't coming up for me at all. Maybe they're coming on a "slow byte from China"?

There is less detail in C but it still looks acceptable. More detail in B and still more in A but the picture is breaking up along the edge of the lighthouse in A. A is the slowest to load.

[This message has been edited by JimJohnson (edited 12-03-99).]

Yep. Tried so many times to get all three to load, I finally gave up in frustration. I don't know WHY the "C" version came up.

Just ignore this thread until Prof. Aucremann figures it out.

I fixed it for you, John.

"A" is starting to deteriorate noticeably along the contrasting edges, but "B" doesn't really look all that bad.

[This message has been edited by Rod Watson (edited 12-02-99).]

What? They all have the same 'ugly' lighthouse! LOL [duck]
The texture and shadows on the color of the lighthouse are not as sharp on 'C less than B less than A'.
You really have to LOOK hard to find it.



[This message has been edited by rscroope (edited 12-03-99).]

"A" seems to have blurring around the edges of the building. I can't tell much difference between "B" and "C", but "C" does seem sharper.

Joanne

A has the most detail, but is breaking up along the edges. C seems to be the sharpest. All loaded in about the same time for me.

A,B,C = Good, Better, Best (but I cheated!)

No noticeable difference (but I left my glasses upstairs, lol!)

Obviosly not! It's just the opposite of what I thought !

Here's what I see...

Colors on B & C are pretty darn close, (both better than A) but B is slightly grainer than C.

There's less information in A than B, and less in B than C. Position your cursor on each picture in turn and click your Right MB. Select the 'properties' option on the menu, then note the size of each pictute in number of bytes. More bytes = more information.

Also note, each picture is the same size in terms of number of pixels. A pixel is a 'point of light' turned on by your monitor. Video resolution is expressed in number of pixels displayed on your screen - for example, 800x600 means 800 pixels wide by 600 pixels high with 480,000 total pixels (points of light) available on the entire screen. 1024x768, 1280x1024 - these resolutions mean more pixels.

Each pixel can have more or less information associated with it, such as 8-bits per pixel or 24-bits per pixel. (A bit is a '1' or '0' and the combination of 1's and 0's give allow for different colors.) The bits that make up a pixel basically tell it different combinations of Red-Green-Blue.

So, while each of JC's pictures has the same number of pixels, in the higher rez picture each pixel has more bits associated with it. The more bits the more different combinations of 1's and 0's - the more different colors. Like an artist who mixes paint to get different combinations of color. 24-bit color is considered photographic quality. Within 24 bits you can have 16,777,216 different combinations of 1's and 0's and thus more colors.

Another factor is the color pallette - the number of colors - supported by your video adapter card. (Click the 'Display' icon in your Control Panel and look at the 'Settings' tab. It should tell your a pallette size and video resolution.) The more colors supported by your pallette choice the more 'refined' images will be when those images contain sufficient information to be refined, ie., more bits per pixel.

The nutshell video resolution primer is offered up by yrs. truly in the Pages at HarbourLights.com thread - 'bout half-way down.

As you can see from JC's examples, the difference are pretty subtle - and the subtlety is partly a function of your computer's video set-up, so not everyone gets the same experience. The lesson to draw is this: unless you've got a darn good reason to create your images with increased color depth, you're better off using 8-bit color for most Web display. The smaller the picture size, the faster the download. And everybody likes a snappy Web page display. :-). Fwiw, the Netscape standard Web pallete is 256 colors.

For those of you who've read both postings on this topic, you may cross off item #17 on your Play Room Merit Badge checklist.

Rgds,
__
/im
[This message has been edited by JTimothyA (edited 12-04-99).]

[This message has been edited by JTimothyA (edited 12-04-99).]

[This message has been edited by JTimothyA (edited 12-04-99).]

All three images came right up on my screen. B & C are very close and look the best. Image A is a little fuzzy in places. My monitor is just a year old.

Bob

to make the following post appear over white.

[This message has been edited by engbrady (edited 12-05-99).]

These are optimized at four different levels from the original PSD before converting to a jpeg.




The more times you save a file as a jpeg the image starts to break down. You in effect are compressing the compression. You should only save an image the one time as a jpeg. If you optimize a jpeg, you are stripping the image of information and when you save it you compress the compression, this adds up to become a degraded image with pixelation and noise being built up.

When you are working on an image and you need to save it over and over again, it needs to be a non-compressed image like a PSD (PhotoShop), BMP (bit map) or such. When the image is ready to be saved the final time, for the Internet, save as a jpeg.

SaintWackoPaul '
Keep the Flame

good tip Pablo!

Amazing how I can pick up subtle differences in the pictures when I never even noticed that each message background alternates between white and gray/grey?!