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SeaOtter

Joined: 21 Apr 2005
Posts: 305
Location: West Hartford, CT
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Posted: Sat Oct 01, 2005 10:47 pm
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I shoot in Raw (Canon cr2 in my 20D). After I open and work on the image in CS2 I've saved the image as a TIF file so I can continue working on it in photoshop. I have 2 questions:
The TIF file is HUGE, about 5 times as large as my Raw file; the raw file is about 8Mb's and the Tif file is over 40Mb's.
and
I cannot save the Tif file in JPeg format. That file option does not appear in the Save As dialogue box.
I've tried saving the file in different formats,e.g. DNG and photoshop format. Same result.
What's the solution?
Thanks a bunch.
Whoa .... a little experimentation ....
If I change the raw workflow settings to 8 bits per channel rather than 16 bits per channel, everything seems fine, at least I can save in Jpeg format.
So now a new question .... what's best for SS uploads?
Ed |
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pcimaging
Joined: 16 May 2005
Posts: 12
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Posted: Sun Oct 02, 2005 12:00 am
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When you use your RAW converter and convert to TIF you need to select 8 bit rather than 16 bit. A 16 bit TIF can not be saved as a JPG. Since I do not know which converter you use I can not tell you where the setting gets changed. However if you look in your RAW cobverter you will find there is an option to make it an 8 bit TIF. Also in Photoshop under IMAGE/MODE there is an option to change the image to 8 bit. Once you do that you will be able to save as a JPG. |
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gracey

Joined: 24 Aug 2005
Posts: 2402
Location: Ontario, Canada
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Posted: Sun Oct 02, 2005 4:18 am
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I work on the file in 16 bit and when complete convert to 8. 16 bit is slower, but has more data. I save the tif file first, then convert to 8 bit to save as a jpg file.
When you open your file in the converter, keep it as 16 bit. It's an extra step, but worth it. You can convert from 16 bit to 8 in photoshop after the work is completed. |
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SeaOtter

Joined: 21 Apr 2005
Posts: 305
Location: West Hartford, CT
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Posted: Sun Oct 02, 2005 11:11 am
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Thanks all!!! |
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SeaOtter

Joined: 21 Apr 2005
Posts: 305
Location: West Hartford, CT
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Posted: Sun Oct 02, 2005 11:13 am
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| gracey wrote: |
When you open your file in the converter, keep it as 16 bit. It's an extra step, but worth it. You can convert from 16 bit to 8 in photoshop after the work is completed. |
Gracy: How do you convert a 16 bit tif file to 8 bit in Photoshop?
Thanks! |
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CarolinaSmith
Joined: 11 Apr 2005
Posts: 200
Location: USA
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Posted: Sun Oct 02, 2005 1:02 pm
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SeaOtter,
In PS, go to Image > Mode > 8bit
That's where you'll find it. Don't give up your 16bit files... meaning that when you save, convert that 16bit to 8bit so you can save it to jpeg, use
Save As a Copy....
not Save...
Yes you will have one more file on your hard drive, but you'll then always have your 16bit file to work on down the road if you want to or need to...
For example if you learn new PS skills down the road, or if you want to make a print from your TIF file (You do want to print from your best file, don't you?). So when you convert a 16bit file to 8bit, then Save As a Copy for the jpeg, just close the original 16bit file (say NO to 'Save Changes?'...).
It's best to keep your options open :) |
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SeaOtter

Joined: 21 Apr 2005
Posts: 305
Location: West Hartford, CT
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Posted: Sun Oct 02, 2005 4:53 pm
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Thanks for the tip Carolina. |
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sk8ter20art

Joined: 06 Jun 2005
Posts: 376
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Posted: Sun Oct 09, 2005 1:19 pm
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.tif,.tiff's, and .tga and other propriatary versions of those file types can exist as 16bit images. Jpegs are not capable of bieng 16bit only 8bit. In older versions of photoshop only a few tools worked in 16bit mode anyway. I do not have CS2 so i cant say anything about that. But the tools are becoming more widespread. Unless you get into the high end software like photoshop, premier, after effects, and shake most programs will not recognize 16bit or convert them to 8bit automatically. |
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sk8ter20art

Joined: 06 Jun 2005
Posts: 376
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Posted: Sun Oct 09, 2005 1:27 pm
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and as always keep an original, work on a copy, and always save in a lossless format like tif or tga. because once you compress a file or resize it smaller you cant go back. Space is getting cheaper by the day so having multiple copies wont hurt. |
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supertramp

Joined: 29 May 2005
Posts: 3818
Location: Lost, but making good time.
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Posted: Mon Oct 10, 2005 10:50 am
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Now is 16-bit better for print over 8-bit? Can you see the difference? I do know that you can get finer control when editing 16-bit, but does it make that much of a difference? |
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feztaa
Joined: 14 May 2005
Posts: 616
Location: Canadia, eh?
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Posted: Mon Oct 10, 2005 12:23 pm
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| supertramp wrote: | | Now is 16-bit better for print over 8-bit? Can you see the difference? I do know that you can get finer control when editing 16-bit, but does it make that much of a difference? |
The way I understand it (and please correct me if I'm wrong), is that the human eye can only distinguish between about 10 million colors. 8-bit RGB images provide 16 million colors, so that is more than adequate for "what the eye can see". The problem is that if you're going to do an aggressive levels or curves adjustment on an 8-bit image, you just don't have a lot of data to work with, and you'll get spikes in your histogram (which shows up as color banding in the actual image). The benefit of working in 16-bit is that you have a lot more data with which to do your adjustments, so when you finally do convert to an 8-bit JPEG, the final results will look good with a proper histogram, etc.
So, yeah. 16-bit has little effect on what the eye can see, but it has big advantages for image editing.
Here's some math I just worked out. An 8-bit image will have 2^8 = 256 colors per channel. Since 8-bit RGB has a red, green, and blue channel, this means that you can make 256*256*256 = 16,777,216 different possible colors. However, a 16-bit image will have 2^16 = 65536 colors per channel, giving you 65536*65536*65536 = 281,474,976,710,656 different possible colors. So as you can see, there's lots more data to work with, giving you a much higher quality file. When you convert from 16bit to 8bit, you're just throwing all that extra image data away, so it's best not to do that until the last possible moment. |
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SeaOtter

Joined: 21 Apr 2005
Posts: 305
Location: West Hartford, CT
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Posted: Wed Oct 12, 2005 8:53 pm
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I won't challenge your math, it looks about right to me. However, most cameras will not capture 16 bit images. For example, the 20D specs say that raw images are 12 bits. But we're stuck in PS with either 8 or 16. So if I use 16 in PS but my camera is actually capturing only 12, I guess the most I get in PS is 12. Can anybody shed light on this? |
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feztaa
Joined: 14 May 2005
Posts: 616
Location: Canadia, eh?
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Posted: Thu Oct 13, 2005 1:04 am
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Oh yeah, my mistake. Camera RAW formats are usually around 12 bits from what I hear.
I do know that although GIMP only supports 8-bit, the RAW import tool supports the full 12 or whatever bits, and it lets you do white balance, color correction, and has a rudimentary levels tool, so basically I can do all that with the full 12 bits, and then import into gimp and just do some quick touch ups with the clone stamp and the crop tool in 8-bit, and save it as a tiff with a beautifully "even" (for lack of a better word) histogram. |
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