File Size and File Type

[wheelhot]

Hi,
Well can someone explain to me why would you save a picture in TIFF rather then JPG or PNG or it doesn't matter?
I know that in web most pictures is saved under JPG and sometime PNG but how about photographs that you keep?
A TIFF picture is sized at 27mb while the same picture in JPG is only 2.4mb, that's a lot of difference.

 

[richard.mac]

i think a TIFF is lossy like WAV on a audio CD or FLAC and JPEG is compressed which sacrifises the image quality. PNG keeps an images transparency if it has it.

 

[wheelhot]

Aaaah, so it means that PNG and JPEG will produce same quality images unless transparency is involved? and TIFF is something like universal RAW saved format?

 

[Digital Skunk]

Aaaah, so it means that PNG and JPEG will produce same quality images unless transparency is involved? and TIFF is something like universal RAW saved format?

More like TIFF is uncompressed and there is no quality loss if you open it and save it again.... no compression whatsoever.

JPEG is compressed and every time you save it it will compress again.

 

[bocomo]

More like TIFF is uncompressed and there is no quality loss is you open it and save it again.... no compression whatsoever.

JPEG is compressed and every time you save it it will compress again.

bingo

also TIFFs can be 16 bit and support layers

 

[wheelhot]

Thanks for the tip guys cause I made a HDR picture and its saved as TIFF with a whopping 20MB so that is a lot. Anyway, why can't Photoshop save a TIFF image as JPEG?

 

[Digital Skunk]

Thanks for the tip guys cause I made a HDR picture and its saved as TIFF with a whopping 20MB so that is a lot. Anyway, why can't Photoshop save a TIFF image as JPEG?

It can, just go to save as instead of just save. Either way, 20MB TIFFs are quite small. When you get a 16 bit TIFF file of a 21MP image with lots of bright colors you are talking more like 256MB. You can hold that in RAM, but your processing power will be greatly decreased depending on your machine.

 

[GT41]

Thanks for the tip guys cause I made a HDR picture and its saved as TIFF with a whopping 20MB so that is a lot. Anyway, why can't Photoshop save a TIFF image as JPEG?

You need to go image->mode->8bit RGB to be able to save in JPEG as far as I know... but someone can correct me if I'm wrong.

 

[MisterMe]

More like TIFF is uncompressed and there is no quality loss if you open it and save it again.... no compression whatsoever.

...

TIFF is most certainly a compressed image format. Unlike JPEG, however, it uses lossless compression.

Read and be wise.

 

[bocomo]

TIFF is most certainly a compressed image format. Unlike JPEG, however, it uses lossless compression.

Read and be wise.

so that's why i have the option to use "No" compression instead of LZW, RLE and JPEG?

the lossless compression options are certainly valuable but not necessary

 

[wheelhot]

Thanks misterme. I don't usually read WikiPedia on terms cause I won't fully understand what it says, I prefer forum for that.

It can, just go to save as instead of just save. Either way, 20MB TIFFs are quite small. When you get a 16 bit TIFF file of a 21MP image with lots of bright colors you are talking more like 256MB. You can hold in that RAM, but your processing power will be greatly decreased depending on your machine.

Aaah, now I know why Pro photographers who post-process will own a MacPro as their working machine. That's huge, I think my MBP (w/ 2GB ram) won't be able to run fluidly with that much of information especially when I'm running, iTunes, Safari, Vuze, Adium at the same time .

Using Photomatix to generate change in a large size photograph already took a few seconds to render and Photoshop -> lens blur in accurate mode take like seconds to change the look of the picture if I change the settings (most of the time I use the quick mode until I'm quite happy with how it looks, only then I change to accurate )

JGEG don't support 16-bit?

 

[Digital Skunk]

TIFF is most certainly a compressed image format. Unlike JPEG, however, it uses lossless compression.

Read and be wise.

Read your own sources.

"the TIFF using lossless compression (or none) may be edited and re-saved without losing image quality; other TIFF options are layers and pages."

You can't save a 16 Bit JPEG, you can convert them to 16 Bit in post, I doubt that would add anything to the IQ even if adding filters, and then you will have to save it as something else.

Sorry, Edge100 gave the simple answer....

 

[Edge100]

Aaah, now I know why Pro photographers who post-process will own a MacPro as their working machine. That's huge, I think my MBP (w/ 2GB ram) won't be able to run fluidly with that much of information especially when I'm running, iTunes, Safari, Vuze, Adium at the same time .

Yup, though I'm not sure how many pros are doing all that while editing...

Get 4GB in that MBP if you can; it makes a big difference while working in PS.

JGEG don't support 16-bit?

Nope. JPEG is 8-bit per channel (i.e. 24-bit RGB).