Best suggestion for printing... Is it better to save your photos that have been edited as 8x10? Will the 8x10 be fine to print in a 5x7 0r 4x6 without affecting any of the edits
around the edges? Thank you
The way images 'should' be saved is as a PSD file.....regardless of what you start with...jpg, png, gif, tiff etc.
Photoshop is an image editor and uses resources such as other images to create a PSD file, from which you can then do whatever you wish....printing included.
Your limitations when it comes to printing are the pixel dimensions of the PSD file. Digital images are measured in pixels, not linear units. It goes without say that the more pixels you have the bigger the image you can print that would be deemed 'acceptable'. In reality any image can be printed at any size but what it looks like may not be 'acceptable'.
With that said, your statement of having an 8x10 (I assume you mean inches) makes no sense......an image only has linear dimensions AFTER its printed on paper. Whilst still in the digital world it contains only pixels.
PS will tell you via IMAGE > Image Size the size of print you will get given the resolution you require.
The higher the resolution the smaller the print, the lower the resolution the bigger the print.
You can also define the size of print you want and let PS calculate the resolution.
Either way, you have a finite amount of pixels (without re-sampling the image, which is to be avoided if at all possible) with which to work.
Your decision on how the final print will look will determine if you sacrifice resolution for size, or size for resolution....that is of course only if you don't have enough pixels to satisfy both conditions.
That all sounds a bit complex but in reality its just simple maths...for eg:
In order for any printing to work the ratio of pixels in the image must equal the ratio of the print required.
So lets assume...
You want an 8x10" print size.
You have an image 800px x 1000px.
Therefore in order to print at that size the resolution needs to be 100ppi:
(800px / 8" = 100)
(1000px / 10" = 100)
Both the width and height resolution have to be equal.
If you are printing this yourself then a resolution of 100ppi may be enough....but if you send this to a commercial printer they may insist on a minimum resolution....this is normally 200-300ppi
So lets do the maths for that situation...
800px / 300ppi = 2.6"
1000px / 300ppi = 3.3"
So @300ppi the biggest print size you could have is 2.6x3.3"
If you need a bigger print then you need to re-sample the image first.
Its therefore important to start correctly with resources big enough to satisfy the required print size at a certain, and often non-negotiable, resolution.
MrToM - I'm quite sure that the OP is asking a much simpler question, namely, whether or not he can get away with storing a rectangular image as a single file with an 8 x 10 aspect ratio and will that file will be suitable to cover possible future needs for other aspect ratios such as 5 x 7" and 4 x 6" without needing to do either unwanted cropping or adding unwanted blank space. I doubt whether he cares (at this moment) whether the numbers in the "8 x 10" designation represent inches, a dimensionless ratio, or numbers of pixels.
The answer to the above question is very simple: No, it doesn't do one any good to store your images at a different intermediate aspect ratio (ie, his suggested 8 x 10 ratio). Any change in aspect ratio (eg, when a derivative with a different aspect ratio is needed), always forces one to either crop or add blank space to get it to conform to the new aspect ratio, so the recommendation is to leave images at their native (ie, as generated) aspect ratio. That way, only one transformation is needed.
Also, the strong recommendation by the US Archives and US Library of Congress is that your archival copy should never be up- or down-rez'ed (interpolated) in any way - - just leave the pixel dimensions the same as they were when the image was generated. If you are interested, I'm sure I can find the exact link to their recommendation on this subject.
The recommendation from Adobe (eg, the workflow in LR) is exactly the same as that of the Archives and the LOC: store images at the dimensions they were initially generated (ie, the aspect ratio of your camera), and then make only one change in aspect ratio to get from it to the needed aspect ratio. In contrast, if you first convert all of your pix to an intermediate aspect ratio (eg, 8 x10 ), then any other aspect ratio will require a second aspect ratio conversion, and you'll always lose more of the picture doing it this way. For example, if your camera puts out images with a 2 x 3 aspect ratio ( which is the same as a 4 x 6 ratio), if you convert the image for long term storage to an 8 x 10, and then need a 4 x 6 print, you will either needlessly lose material at the edge of the frame or have to add "padding". This is *precisely* why Lightroom always stores images at their native sizes and provides a large number of preset printing and export presets.
Secondly, I hate to say it, but your recommendation to use the PSD file format (presumably, for archival storage of the OP's images) is at variance with the recommendations of all major, well respected groups who have considered the issue of archival storage. For example, here are recommendations from Stanford U, Harvard U, and Cambridge U:
The standard recommendation for archival storage of stills is as TIFs.
PSDs are fine as a way to preserve a working copy that you might want to re-edit at some point in the near future, but for the long term, the PSD format is not recommended because (a) it is a proprietary, not open format, (b) it changes over time, and (c) it is quite susceptible to bit rot, just like JPGs. If you think this is a theoretical concern, I have personally had about a dozen of the PSDs in my large archive become useless because of bit rot over the time scale of 10 - 15 years, and this is even with migration of the archive to new physical media every few years.