A case against JPG

[TKP]

i was thinking more of a RAW format, but i've never used one with it... i dont know, but its possible that it could do that same thing that yours did with TIF...

And to be honest, I never decrease the quality of my pictures. For me there is no reason to, I've got a good amount of HDD space for em, and a 512 CF card in my camera (Canon Powershot A75 in case you were wondering).

[Theophylact]

I use a Canon PowerShot S45; Marcia uses a Canon ELPH SD300. Both are 4 megapixel cameras that will let you save RAW images, although the jpegs are good enough for all practical purposes. Just get a large enough storage card. I use a 1 Gig compact flash; she uses a 512 MB SD. Memory prices are really low, and 4 megapixel is becoming entry level these days; I've seen her camera for less than $270.

[DanU]

I've always used lossless formats (GIF, PNG) for images with high contrast computer generated graphics and text. For these files, PNG is often SMALLER than JPEG. The lossless LZ and Huffman compression schemes excel at squeezing these types of files down in size. I've seen typical compression ratio of 10 to 1 with most of the images I've created at work. When these images are converted to JPEG, the compression ratio is about the same but the images look terrible because JPEG doesn't handle high contrast edges very well.

For photographs and other images that have more "natural" changes in color and brightness, JPEG is perfectly acceptable and may even be superior depending on the situation. Given a limited file size, a JPEG can be more accurate than a PNG. In a sense it uses it's bits more efficiently by encoding only the most important information in an image. Compression ratios of 20 to 1 can yield very good images. In contrast, the lossless compression scheme used in PNGs is poorly suited for this type of data. You can expect maybe a 2 to 1 rato. For sharing photos over the web, where bandwidth is an important consideration, JPEG is ideal.

Which one should you use? That's up to you. Weigh the advantages and disadvantages of each and you'll see that there's no best format for all situations.

[OuTpaTienT]

Quote:

Originally Posted by DanU

Given a limited file size, a JPEG can be more accurate than a PNG.

More accurate? What do you mean by that? If PNG is lossless how can you be more accurate than that? Doesn't make sense. If something is 100% correct then something else can't be more correct.

Yes jpg is the preferred format for sharing images, especially over the net. But I wouldn't choose it as an archival format if given a choice.

[DanU]

Let me rephrase that... given the SAME file size, in certain situaitons a JPEG can be more accurate than a PNG. If I had an uncompressed 1MB photograph and had to compress it so it will only be 100KB (say my boss drew the line at 100KB for images on a web page), a 100KB JPEG will look very good. In comparison, in order to get a 100KB image using PNG, I would have to resize the image to a lower resolution by about 1/5th and then convert it to PNG, because it can only compress by about 2:1 for complex images like photographs, in order to get down to 100KB. The process of resizing the image down by 1/5th will throw away far more information than compressing via JPEG

For archiving you generally want to keep as accurate a record a possible, so I can see the preference for lossless compression. However practicality does impose some limits with regards to file size. Personally I find JPEG at a high quality setting to be a good compromise of excellent quality and good compression for photographs. I don't scrutinize my photos with a zoom lens so I'll never see the difference.

[CookieBox Inc.]

I'm ok w/ the jpegs since it's so widely used, even though it's not a workable medium since you loose quality each time you save. I still say PNG is better if you want quality, and if you want speed, gif is the way to go! ...i personally don't use jpeg much at all...lol...the way they load on a webpage just pisses me off.

[ry4n]

The biggest reason why PNG is so great is its transparency. JPEG doesn't have transparency, GIF transparency is quite useless if your using any kind of curved edge. If you try using GIF transparency with a curved edge it will turn out blotchy, and even when you tweak it the edge will not be smooth like you see in the PSD. The PNG transparency, even on curved edges, is just as smooth as you would see in the PSD file. What is the use of transparency? Well for Web designers it is pure gold.

[JayMan]

Quote:

Originally Posted by ry4n

Well for Web designers it is pure gold.

Except that probably the most used browser (internet explorer) has a bug that doesn't render PNG's with transparency properly.

As far as i know that issue has still not been fixed.

JayMan

[OuTpaTienT]

Quote:

Originally Posted by JayMan

Except that probably the most used browser (internet explorer) has a bug that doesn't render PNG's with transparency properly.

As far as i know that issue has still not been fixed.

JayMan

But there are ways to make it display PNGs with transparency correctly which web designers should be aware.

[JayMan]

ah nice, didn't know that :o)

JayMan