File size when saving?

[Maxineovelar]

Hi everyone
A little confused as to how to save my images after editing in photoshop.
What should the image size be when saving? should i be saving 8bit or 16bit? if i wanted to print onto a large canvas.
Im shooting in raw, image is 300dpi.
This is the part of photography that really confuses me the most.
Is there any tutorial anywhere that could make this all a little clearer for me??
Thank you in advance for your help.

[ricktas]

Depends on your printer. Contact them and ask what file formats they recommend. If they say JPG, then save in the highest quality possible. Some good printers will also take TIFF etc files, which will be a lot larger (kb size) but are not a lossy format, like JPG is.

[ameerat42]

...A little confused as to how to save my images after editing in photoshop.
What should the image size be when saving? should i be saving 8bit or 16bit? if i wanted to print onto a large canvas.
Im shooting in raw, image is 300dpi.
This is the part of photography that really confuses me the most.
Is there any tutorial anywhere that could make this all a little clearer for me??...

Hi Maxine.
I'll try to address your several Qs.
The last 1st: I could not (quickly) find a tutorial specific to re-sizing photos for printing, BUT, this one (http://www.ausphotography.net.au/forum/showlibrary.php?title=Tutorials:Resizing_photos_for_the_net) in the Library uses the same techniques for posting on the web - ie, for re-sizing.
It illustrates Photoshop, but...

Now, you say that you shoot in raw and that your native file size shows 300 dpi.
Note that any mention of DPI is not a fixed figure for measuring file size. I don't know your camera, but I'll presume some APS-C model, about 18MPx.
It will produce raw files at say, 18MPx, not DPI, and the DPI value you see is an arbitrary one to give a certain (maybe optimal?) file size when printing.
Furthermore, there is the actual file size in Megabytes to consider. The Library article shows an original file size of "43.8 M" (Megabytes).

If you look at that Library article, you will see that in the re-sizing box there is an option labelled "Resample Image". Here it is ticked, so that the image can be REDUCED in actual file size - not just physical printing size - to something suitable for the web, such as here on AP. What you see are the original file settings, and you change some of the values in the boxes to reduce (or enlarge) the file size AND picture size. Doing either one of these actions will result in either losing original information, OR, adding redundant information to the image.

Now, if you DO NOT tick that "Resample..." box, you will retain all the information you originally retained and saved (in TIFF or JPG format) from your raw file.

If your printing firm wants the best quality (I haven't got much experience with their requirements) then you'd save almost everything from your original raw in a 16-bit tiff, at full size, and in a Color Space they suggest, like Adobe RGB. I suspect that they usually have less stringent requirements, though.

About saving for everyday use. I will illustrate what I do and why (and may any lack of logic be excused).
From the original raw I make tonal and color adjustments and if there is little appreciable change from the original image, I save it straight as a full-size jpeg. If, however, I need to work more on tones and color, or anything that the raw converter won't do, I usually save it as a 16-bit tiff to then work on further in Photoshop.

The Change from original 12-bit raw to 8-bit jpeg will lose original color/tonal info, but the loss will not be noticeable.
The change from 12-bit raw to 16-bit tiff will take up some more filespace to contain no additional info, but to retain (most of) the original info.
When I have done any further editing in Photoshop I save the result as an 8-bit jpeg. A version of this will then be re-sized to fit in the AP posting requirements.

Sometimes I do not keep the intermediate 16-bit tiff - at 100+ MB each they soon soak up disk space.

A general point on printing large sized images: Until the printing firm specifies what it wants for your request, keep the file size you intend to use for this at a maximum. In the foregoing, keep it as a suitable tiff or large jpeg.

A tip about saving jpeg files: Do not just overwrite what you have edited, but save a new version each time.
For example, if you had a nice pic and wanted to BOTH get a large print made AND display it here on AP, then save two different versions:
In Photoshop, choose File - Save as..., then:
1) nice-pic-to-print-big.jpg at MAX quality of 12

Resize the image as in the foregoing and library article, then File - SAve as...
2) nice-pic-to-show-on-AP.jpg at a quality setting of about 8 or 9

When you have finished, DO NOT then (re-)save the changes you just made to the image. It asks you this sometimes.


Well, you have reached the end of this missive (good or bad).

See how you go.
Am.

[Maxineovelar]

Thank you Rick, i tried TIFF and the image was very pixelated, i was told that the image was too large? is that correct??

- - - Updated - - -

Thank you so much for your time Am, i guess i still have a lot of reading to do regarding file sizes etc!! and learning this whole pixels per inch thingy?? but thankyou very much for info above, it helped.
I pretty much do what you are saying as above. I guess i just have to adapt image to fit the situation.
A little apprehensive about using TIFF as i went to have it printed and it was very pixelated!! I was heartbroken, but then discovered that the file was too large, or so they say.
Im shooting with a Canon 60d but wishing for a Canon 5d.......ill keep dreaming and learning.
thank you very much

- - - Updated - - -

Thank you so much for your time Am, i guess i still have a lot of reading to do regarding file sizes etc!! and learning this whole pixels per inch thingy?? but thankyou very much for info above, it helped.
I pretty much do what you are saying as above. I guess i just have to adapt image to fit the situation.
A little apprehensive about using TIFF as i went to have it printed and it was very pixelated!! I was heartbroken, but then discovered that the file was too large, or so they say.
Im shooting with a Canon 60d but wishing for a Canon 5d.......ill keep dreaming and learning.
thank you very much