Re: saving jpegs in another format?

[Terry <terry@xxxxxxxxxxxxxxxxxxxx>]

Hello Herschel

I think you still loose information each time you adjust a photo file weather you use PS or another photo editing program, and no matter what format you save it to, just by making a simple color change you loose information do this enough and you start to get banding, there is no way around it make enough changes to the same image file and you will loose it, and I don't think layers will help assuming you make the adjustments and flatten the image for printing.

At lease this is what I have been told in my work flow seminars, and have read in digital photo pro, and rangefinder mag, to name two.

 

Personally I am not a fan of jpg, I only shoot jpg when I am taking snapshots and know I will not be making adjustments to them and just want them for memories, every thing else is shot as RAW, and most are saved as RAW, the exception to this are photos that I have worked on to correct color and remove unwanted items and are sold as fine art, those are saved as TIFF files, and I am not advocating TIFF over the other non lossy formats it is just what I am familiar with, once I have my files ready to print ( in the case of portraits ) I do convert to jpg and then FTP them to my printers, tests have shown that once all the changes have been made to a photo file and then converted to jpg it makes no difference in printing, my lab took TIFF files, printed them then converted the files to JPG printed them again in large print sizes and you could not see any difference, but no changes where made to the file once it was converted to JPG.

Terry L. Mair
Mair's Photography
158 South 580 East
Midway, Utah 84049
435-654-3607
www.mairsphotography.com

----- Original Message -----

From: herschel mair

To: List for Photo/Imaging Educators - Professionals - Students

Sent: Thursday, May 12, 2005 11:27 PM

Subject: Re: saving jpegs in another format?

Hi again Terry

The PNG file format is a pretty good one although not all applications support it. If you're using photoshop, the best format to save your working images as is thye photoshop format (.psd) That way you can make adjustment layers, snapshots etc. and keep everything together in case you want to change it later. Disk space is really cheap now and there's no reason to recompress your Jpegs. Most places can print from PSD files too.Tell them bnot to touch anything.

 

Herschel

Terry <terry@xxxxxxxxxxxxxxxxxxxx> wrote:

Terry L. Mair
Mair's Photography
158 South 580 East
Midway, Utah 84049
435-654-3607
www.mairsphotography.com
----- Original Message -----
From: "Andrea Coffey"
To: "List for Photo/Imaging Educators - Professionals - Students"

Sent: Thursday, May 12, 2005 9:51 PM
Subject: Re: saving jpegs in another format?


> At 22:46 12 05 2005, Sally Mack wrote:
>>When I get my film processed, I order CDs as well as prints. The files on
>>the CD are jpegs which I then edit. I understand from various sources
>>that the jpeg format loses data.
>
> That is correct. The extent of loss / how much compression is applied, can
> be set in many programs. I've found juggling the compression level more or
> less can find an acceptable compro mise of file size and image output
> quality. This can often be a long way from the common default of 85%
> compression.
>
>>Should I save the jpegs as tiffs or some other file format? If so, at
>>what point should I save in another format, immediately, before editing?
>>After editing?
>
> Once the image has been loaded into a program, then there are no
> "accidental" losses of data. It's when the image is _saved_ as a JPG that
> the losses occur, in the saved file. If you keep editing, the data is
> still complete (as originally loaded) in the program.

As I understand it each and every time you make an ajustment to an image you
loose data,
TIFF, PNG, JPG, it doesnt matter, once you make an adjustment you have
changed information and have
lost information this is why 16 bit is getting popular you only loose half
or less of the
information as you would loose in 8 bit.
>
> I find it useful to load the image, and immediately do a "Save As..." with
> a different name specified, so I don't lose the original image. A useful
> format for me is PNG, which is not "lossy", so the one file can be
> repeatedly opened, edited and saved without deterioration. Thus, if I
> start from a JPG, I'll immediately open it, save as PNG, and then work
> from there. (Of course, opening the _original_ JPG, which has not been
> saved over-the-top will still have all the information it ever contained.)
>
> The Pentax Photo Laboratory will only save JPG (five levels of
> compression) or TIFF (8- or 16-bit), so I save my PEF (Pentax RAW) as
> TIFF, then open the TIFF in The GIMP, and save as PNG. (Then delete the
> TIFF, since they are _much_ larger than PNG, with no extra information.)
> Alternatively, I'll open the PEF in IrfanView Thumbnails and save directly
> as PNG.
>
>
> &i (:
>
>

Herschel Mair

H.O.D. Photography Dept, Higher College of Technology
Al Khuwair
Sultinate of Oman
9899673

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