http://en.wikipedia.org/wiki/Ad_hominem

Bagginsbill you're smart and all, but when anyone ever questions what you say, even when what you say is problematic or simply wrong, you immediately get rude rude rude as fuck fuck fuck.  Seriously, rude rude rude as fuck fuck fuck.  It would be great if you made some small effort to control your immense rudeness reflex at least some of the time.  Thanks.

Thanks pjz99
My English is not so good that I could answer to this rough tone rationally.

Quote - Bagginsbill you're smart and all, but when anyone ever questions what you say, even when what you say is problematic or simply wrong, you immediately get rude rude rude as fuck fuck fuck.  Seriously, rude rude rude as fuck fuck fuck.  It would be great if you made some small effort to control your immense rudeness reflex at least some of the time.  Thanks.

If the moderation here is not willing to muzzle him, why exactly should he be polite ?

Quote - http://en.wikipedia.org/wiki/Ad_hominem

Bagginsbill you're smart and all, but when anyone ever questions what you say, even when what you say is problematic or simply wrong, you immediately get rude rude rude as fuck fuck fuck.  Seriously, rude rude rude as fuck fuck fuck.  It would be great if you made some small effort to control your immense rudeness reflex at least some of the time.  Thanks.

he won't. this has been pointed out many many times before. each time a justification about being allowed to because of being smarter, having been educated etc was given, as if that excuses the behavoiur I doubt he lets his children get away with.

".TIFF"s taste great, ".JPG"s are less filling.....

OpenEXR are an all you can eat buffet :p

I have never found BB to be rude.  Abrupt, yes.  Rude, no.  You all must be living in fluffy bunny land if you think someone disagreeing with you - and giving specific reasons why - is being rude.

Only person I saw being rude here was Haarspalter.

This was his response to Acadia:

"Why do members of this forum have to spout the equivalent of old wives tales over and over and over. Is it just impossible for any of you to try proving anything?"

That is basically character assasination, not 'abrupt.' And hillariously enough, he didnt even manage to 'prove' anything himself so not only was he rude, he was rude and incompetant. Or is that too abrupt an assessment ?

Behave people, behave.

This thread is about image formats, not personality traits of individual members. If you have something personal to sort out, take it to private messages please.

I'm never rude, I'm so sweet :wub: Don't you just love me? I shall brandish my trusty sword and beat up that nasty bagginsbill for you. (hearing footsteps stepson scampers off to hide in the dark basement.)  :laugh:

Most people arguing in this thread seem to have come armed with a knife to a gunfight :tt2:

Quote - Most people arguing in this thread seem to have come armed with a knife to a gunfight

I've come armed with a bag of marshmallows.

The big, puffy kind.

So... watch out.  :scared:

You guys inspired me to conduct my own JPEG experiment. My tests and procedures can be found on my blog here, but these are my basic conclusions:

• An image that is repeatedly saved as a high-quality JPEG will degrade slightly, but only slightly.
• JPEG quality can vary extremely widely, and it only takes one save as a low-quality JPEG to seriously degrade an image.

The blog article also has links to all of the pictures I generated while testing.

Quote - So I repeated the experiment, in Paintshop Pro instead. Surprise! No banding. No dimples. Well, it's there though, after a very close investigation (take difference, and increase brightness to +100 and contrast to +60 in an additional adjustment layer). But the dimples are less deep, and about 4 times wider spaced.

I don't know what PaintShop does, but you can get rid of the color bands adding random noise with levels less of 1/256. With the same method you can produce 16 bit color (65K) that look similar and without banding as true color 24 bits (16M). Adding random noise reduce the artifacts but increase slightly the file size. You can do many things with software.

Telling that an image was saved as #12 is meaningless, I don't use Photoshop and the level 12 is basic Chinese for me. JPEG format allows to set different parameters for the compression, you not only can set the amount of compression, you also can set the color bandwidth reduction scheme. It looks as PaintShop Pro is much flexible than PhotoShop and allows you to set different compression schemes.

No matter how are your settings, always something is lost due the compression, even the quality is set to the maximum of the maximums.

One important to take into consideration is that mp3 and jpeg are subjective compression methods where something is lost forever. What was lost is as the name tells. is subjective and so it depend on the person that see or hear the compressed data.

In the extreme, a blind person will not see any difference between a color and a black and white image. For him all is the same and nothing was lost removing the color information and if you insist that the images are different, if he is a rude person, he will reply f*&*# y@! and all the classic known bla bla bla.

It was an extreme example, a blind person see nothing and so he is unable to see any difference. In normal cases, one person do not see or hear the same as other. Some people has more acute sight and perceive more than other and also your vision capabilities improve with training and use. With age you can lose your vision due to some disease, but even with this you perceive much more than when you was young. NOTE: A blind person with some training can tell you which image is in color and which is B&W.

What to do? A simple rule. Save the image in png and jpeg, if you see that the saved png image looks better than the saved jpeg image then discard the jpeg and keep the png. If you perceive no difference then you can save in jpeg. In professional work where the target audience requires high quality you always must save in png of tiff even you don't see any difference. Remember that your client can have a much better perception than you have and he is able to see differences that for you don't exist.

Quote - Bagginsbill you're smart and all, but when anyone ever questions what you say, even when what you say is problematic or simply wrong, you immediately get rude rude rude as fuck fuck fuck.  Seriously, rude rude rude as fuck fuck fuck.  It would be great if you made some small effort to control your immense rudeness reflex at least some of the time.  Thanks.

lol. Said the pot to the kettle!

from digital photography i went to tif always, and it's tif always for me.  if i need transparency i save as png also and use it as a mask.

jpgs have always seemed (from photography, so i use it here too) very lossy and grainy to me.

and after all, why throw out part of the image if you don't need too? 

Now from a technical and strict academic point of view.

Beware of your tests, tests must be done in a correct way if not you get flaved results and the most weak point is your source image used for the tests.

The source image that you use as starting point must be an image that never had been compressed in jpeg format. If the image was once compressed with jpeg, the first compression has removed almost all the information to be analysed. Further compression will remove very little and can led you to the wrong conclussion that nothing was lost.

You can be doing wrong the tests, you download some image in png format, then use this image for the tests, compress in jpeg, compare the two images and reach the conclussion that is all the same, but you can be wrong because the image that you used in the tests once was compressed in jpeg, who knows how much it was compressed and then some other person took this image and uploaded it in png format.

You must use vigin images for the tests, images that never has been saved in jpeg.

From where can you get these images? The better source is a good digital camera with images saved in a loseless format. Scanned images of photographs are not very good, unless you have a very expensive professional scanner the scanner performs some compression and interpolation.

Another good source can be quality CD collections or even downloaded where you believe that the original quality of the image was preserved in all its past history. The images are big in size and in file size.

Another good source are images generated by software as gradients and patters. It are good for testing artifacts, but not for quality tests.

Rendered images are not good for tests, it doesn't matter if you saved as psd or png. Rendered images have little high frequency components, so much less is lost in a further jpeg compression. A photo has much more high frecuency componets and so much more is lost if you later compress in jpeg.

For an theorical and academic test:

1- Take some image in png format and save it in png format.

2- Take again the png image and save it in bmp format (must be bmp!)

3- Take the saved jpeg image and saved it also in bmp format.

4- Use some software to compare both bmp files.

5- Count the number of bytes that are different in these two files

6- Divide the different bytes by the file size and multiply by 100

7- Now you have in percent how much different are the png and jpeg.

8- If you get small or very big numbers, what does it mean?

9- Well, it is subjective and don't be rude with the answer....

I was intrigued by the JPEG compression and I did a small experiment using Gimp 2.6.10 in Windows. Gimp uses libjpeg for JPEG handling.

I made an image with a gradient, antialiased text and two shapes: one curved and one aligned with the pixels. See below:

I loaded the image saved it to JPEG and closed it to make sure the data in memory was not used to save the image. The JPEG settings were 100%, optimized, no smoothing, not progressive, 2x2, 1x1, 1x1 subsampling and Integer DCT. I did this 10 times and the resulting image is shown below:

After 10 open/save cycles the image is basically unchanged from the original JPEG. Taking the difference between #10 and #1 and shrinking the color curve to cover only the part of the histogram showing data shows that the image does change but so slightly than for most purposes it is undistinguishable from the original. As expected the largest changes are around the sharp edges of the text and shapes. See enhanced difference below:

Obviously this will vary with other software implementations and methods but I doubt the differences would be too large while using 100% JPEG quality.

Although JPEG with 100% quality will work well I would recommend PNG. Hard drive space is cheap and with PNG there is no worry that the software you use would use a quality setting that may mess up your images at save time.

FlyerX

The background noise in the jpeg image of this example will make difficult to have a clear selection of the circle or text using the white color for selection.

This could have been such a good learning thread. But because of attacking eachother it is now locked.