Helen wrote,

[I'm replying to the group so others can shoot me down if I'm wrong...]

> I've tried to understand your disinctions   (and thank you, I appreciate
> it) but I just can't
> understand the relevance.   I'm going to re-read.   Not trying to be
> dense, but, whether
> I call it a file or a display of pixels, the sticking point is that
> after I export to .jpg or
> .png, I want that file (yes, I think it's a file) with the name
> orchare-scaled.png to be
> on my screen and be editable.   And it isn't. 

Please explain what you mean by "it isn't" "on my screen." Previously
you have used the word "disappears". Perhaps give exact, step-by-step
keystroke/menu selections that you use and what happens.

>     > I then had that Orchard-scaled.png on my screen and I could make
>     changes if
>     > I wanted to before mailing it.
>     No, you do not have a ".png" "file" on your screen. You have a display
>     of pixels that were unchanged when you saved to disk as .png.
> Well, but see, I dn't have that display of pixels, whatever we call it. 

Please explain, as above.

> If I want
> to edit that "file"  I have to open it.  It opens with .xcf extension. 
> I love the
> .xcf extension when I'm working on it, but not when it's time to mail it.
>     > It seems I can't do that any more.
>     Nothing has changed in that regard.
> Well, it has for me.  I still have GIMP 2.6 on ubuntu laptop (but I
> don't want to work long
> hours on a thinkpad) and it clearly has changed.  I think I have not
> been able to explain
> clearly, but GIMP -- at least at my house -- will edit only an
> assortment of pixel which
> contain a filename with an .xcf extension.

GIMP will open any image file (that it is able to), not just .xcf files.
Strictly, for non .xcf files, it will "import", but that is transparent
to the user.

Consider .jpg as an example. Such a file is stored on disk in a
compressed format. When GIMP opens it, it uncompresses the data and
turns the information into "a display of pixels" on the screen. That
information is now in memory, uncompressed.

I can't remember how 2.6 named the image window, but if it said
"Orchard-scaled.jpg" (or png) it simply means that that is the file that
was opened. It does not mean the contents in memory are in the same
format as the data on a disk file of the same name.

(See http://gui.gimp.org/index.php/Save_%2B_export_specification for
more details of how the title of the image window and naming works.)

In short, once you are editing an image, forget about the format of the
file that was opened. It's no longer relevant. GIMP is working on a
different "arrangement of pixels."

It's only when you save or export to disk again that GIMP will rearrange
those pixels into a form required by the external file format.

In the case of .jpg, which is a lossy format, the saving process (2.6),
or the export process (2.8), will throw away information that is deemed
to be (relatively) unnoticeable to the human eye. But what remains in
memory (whichever version of GIMP) is the complete lossless image.

Repeating: what is in memory is not a .png, .jpg. .gif or whatever,
format anymore.

Which is why if a .jpg is repeatedly edited/saved (exported)/reopened it
will lose quality.

> I'm trying to understand but will have to go over this again.  I do
> appreciate your patience.
> Helen

Hope that helps.

Bob Long

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