Invertin content of a picture, eg Powerpoint

[Salmon Egg]

Suppose you have a photographic negative as a file in your computer. You
want a positive. It is easy enough to display using inverse video from
UniversalAccess. Suppose, however, you want to print a positive image or
use a positive other purposes, say in a PowerPoint slide.

How do you go about it. I presume that in can be done using Photoshop.
Is it possible to do so with tools in Mac OS or with tools in PowerPoint
itself? Just because you see the image correctly in inverse video does
not mean that you can print it that way.

--

Sam

Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.

 

[Christoph Gartmann]

Suppose you have a photographic negative as a file in your computer. You
want a positive. It is easy enough to display using inverse video from
UniversalAccess. Suppose, however, you want to print a positive image or
use a positive other purposes, say in a PowerPoint slide.

How do you go about it. I presume that in can be done using Photoshop.
Is it possible to do so with tools in Mac OS or with tools in PowerPoint
itself? Just because you see the image correctly in inverse video does
not mean that you can print it that way.

You may use GraphicConverter (a shareware). Or, while displaying the inverted
picture, make a screen-shot.

Regards,
Christoph Gartmann

--
Max-Planck-Institut fuer Phone : +49-761-5108-464 Fax: -80464
Immunbiologie und Epigenetik
Postfach 1169 Internet: gartmann@immunbio dot mpg dot de
D-79011 Freiburg, Germany
http://www.immunbio.mpg.de/home/menue.html

 

[dorayme]

You may use GraphicConverter (a shareware).

That is not a Mac tool.

Or, while displaying the inverted picture, make a screen-shot.

And wtf would that accomplish?

 

[Christoph Gartmann]

That is not a Mac tool.
http://www.lemkesoft.com/


And wtf would that accomplish?

Macintosh-HD -> Applications -> Utilities -> Grab

Regards,
Christoph Gartmann

--
Max-Planck-Institut fuer Phone : +49-761-5108-464 Fax: -80464
Immunbiologie und Epigenetik
Postfach 1169 Internet: gartmann@immunbio dot mpg dot de
D-79011 Freiburg, Germany
http://www.immunbio.mpg.de/home/menue.html

 

[AES]

And wtf would that accomplish?

[/QUOTE]

A couple of quick tests seem to show that B&W-inverting an image on
screen (Cmd-Option_ctrl-8), doing a quick screen grab of the inverted
window or screen area using Grab, and Saving the result to disk does
_not_ create an inverted image.

Interesting, and somewhat surprising -- Grab, or "Screen Capture", is
not in fact capturing the actual screen pixels. Wonder what technical
or other decisions lie behind that? Is it saying that the B&W inversion
is something that is not done computationally, but occurs only in the
electronics after the graphics card and memory? That the inverted pixel
numbers are never actually all present in RAM in the computer, but are
only generated/inverted one by one, on the fly as each (uninverted)
pixel is read out and sent to the screen?

 

[Salmon Egg]

Macintosh-HD -> Applications -> Utilities -> Grab

I do not think that would work. I ha ve taken Grab shots of the screen
in inverse video. It gives a picture in inverse video. I do not know how
that will help you to see two adjacent picture, one positive and one
negative simultaneously.

I have looked at all the menu commands without finding anything suitable.

--

Sam

Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.

 

[Salmon Egg]

A couple of quick tests seem to show that B&W-inverting an image on
screen (Cmd-Option_ctrl-8), doing a quick screen grab of the inverted
window or screen area using Grab, and Saving the result to disk does
_not_ create an inverted image.

Interesting, and somewhat surprising -- Grab, or "Screen Capture", is
not in fact capturing the actual screen pixels. Wonder what technical
or other decisions lie behind that? Is it saying that the B&W inversion
is something that is not done computationally, but occurs only in the
electronics after the graphics card and memory? That the inverted pixel
numbers are never actually all present in RAM in the computer, but are
only generated/inverted one by one, on the fly as each (uninverted)
pixel is read out and sent to the screen?[/QUOTE]

IIRC from old Mac books like Macintosh Revealed or the Apple series of
"telephone" books, there was the fundamental data in undisplayed
windows. Then there a whole series of commands to display that window
including things parameters for position, size, etc. It was also
possible to have logical byte computations where one would be a
complementary color to the one in the data. Although I am sure the
details have changed, I am pretty sure the fundamental plan has not.

--

Sam

Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.

 

[isw]

Suppose you have a photographic negative as a file in your computer. You
want a positive. It is easy enough to display using inverse video from
UniversalAccess. Suppose, however, you want to print a positive image or
use a positive other purposes, say in a PowerPoint slide.

How do you go about it. I presume that in can be done using Photoshop.
Is it possible to do so with tools in Mac OS or with tools in PowerPoint
itself? Just because you see the image correctly in inverse video does
not mean that you can print it that way.

You need an image app that knows about "curves". Because of the
nonlinear way that "gamma" affects images, it takes more than a simple
inversion of the levels to get a decent-looking gray scale -- you need
to manipulate the gamma curve until the image "looks" right. I don't
know of any Apple "included" apps that can do that. In addition to
Photoshop, the GIMP can, and it's free.

Isaac

 

[Erik Richard Sørensen]

Suppose you have a photographic negative as a file in your computer. You
want a positive. It is easy enough to display using inverse video from
UniversalAccess. Suppose, however, you want to print a positive image or
use a positive other purposes, say in a PowerPoint slide.

How do you go about it. I presume that in can be done using Photoshop.
Is it possible to do so with tools in Mac OS or with tools in PowerPoint
itself? Just because you see the image correctly in inverse video does
not mean that you can print it that way.

Use Photoshop, open the file, mark it and 'select all', - then hit COM+R
and you get a positive out of a negative - or visa-versa. Then use 'Save
as' to avoid spoiling the original file. - That's it....

Cheers, Erik Richard

 

[Erik Richard Sørensen]

That is not a Mac tool.

WHAT???????? GraphicConverter is one of the oldest and best graphics
shareware applications and converter app for Mac made by Torsten Lemke.

http://lemkesoft.com/

...Btw. - I've been using it since ver. 1.5 from somewhere around 1994.

Cheers, Erik Richard

 

[dorayme]

WHAT????????

It is not a little app that comes in Utilities or with Mac OS out
of the box !!!!!!! (did I get as many ! as your ? ? <g>)

Here is a way to do it on a modern Intel Mac that can run a
Windows IE browser:

1. In a text editor:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html;
charset=utf-8">
<title>Invert an image using CSS</title>
</head>
<body>
<p><img style="filter: invert;" src="whateverPic.png"
alt=""></p>
</body>
</html>

2. Load up to a server.

3. Open IE and take a screenshot and Bob suddenly becomes your
uncle.

 

[isw]

It is not a little app that comes in Utilities or with Mac OS out
of the box !!!!!!! (did I get as many ! as your ? ? <g>)

Here is a way to do it on a modern Intel Mac that can run a
Windows IE browser:

1. In a text editor:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html;
charset=utf-8">
<title>Invert an image using CSS</title>
</head>
<body>
<p><img style="filter: invert;" src="whateverPic.png"
alt=""></p>
</body>
</html>

2. Load up to a server.

3. Open IE and take a screenshot and Bob suddenly becomes your
uncle.

That will, accurately, invert the value of each pixel (black => white
and white => black). It will not, however, produce anywhere near a
visually optimal image. To do that, you simply must manipulate the
"gamma" (the "curvature", sort of, of the relationship between pixel
value and brightness) of the image.

Isaac

 

[dorayme]

That will, accurately, invert the value of each pixel (black => white
and white => black). It will not, however, produce anywhere near a
visually optimal image. To do that, you simply must manipulate the
"gamma" (the "curvature", sort of, of the relationship between pixel
value and brightness) of the image.

Gamma, shmamma, if you can't be bothered to have and open up a
decent image program, then this would be one of the methods a
bloke would richly deserve, no? <g>

 

[Alan Browne]

Suppose you have a photographic negative as a file in your computer. You
want a positive. It is easy enough to display using inverse video from
UniversalAccess. Suppose, however, you want to print a positive image or
use a positive other purposes, say in a PowerPoint slide.

If it's a scan of a color negative (and wasn't made positive at the time
of the scan (the normal practice), then you first have to blue filter
out the orange mask from the negative (while it's still a negative), and
then invert it (photoshop has a function for that). The steps to do the
orange mask removal can be found somewhere out there via Google.

But again, the _usual_ practice during scanning is to make a positive
image and not save a negative image.

If it's a B&W negative, then it's a simple inversion - and usually some
degree of contrast/bright adjustment to get a satisfying result.

How do you go about it. I presume that in can be done using Photoshop.
Is it possible to do so with tools in Mac OS or with tools in PowerPoint
itself? Just because you see the image correctly in inverse video does
not mean that you can print it that way.

Don't know. But if you don't have photoshop I'm sure the GIMP
(freeware) would have the inversion function.

 

[Alan Browne]

You may use GraphicConverter (a shareware). Or, while displaying the inverted
picture, make a screen-shot.

A screen shot is shown at about 1/3 the resolution of a print. eg: if
it's about 30 cm high on the screen it would print to about 10cm on the
printer. Not satisfying at all.

A scan from a negative with a common film scanner can be (eg) 7600
pixels high by 5100 pixels wide - won't fit on the screen to be
screen-shot printed. (Minolta DSE 5400 scanner).

 

[AES]

I'm still hoping to learn from someone the technical explanation of why
a standard screen grab of an inverted image or window as seen on a Mac
screen, made using Grab after the screen display has been inverted using
Cmd-Option-Ctrl-8, is not captured or stored as the inverted image.

[In other words, Grab is NOT a WYSIWYG operation -- at least, not in the
attempts I've made.]

 

[Erik Richard Sørensen]

I'm still hoping to learn from someone the technical explanation of why
a standard screen grab of an inverted image or window as seen on a Mac
screen, made using Grab after the screen display has been inverted using
Cmd-Option-Ctrl-8, is not captured or stored as the inverted image.

[In other words, Grab is NOT a WYSIWYG operation -- at least, not in the
attempts I've made.]

A screenshot of any kind will always follow the system and be 'as is' -
i.e. if the screen is inverted using the COM+ALT+CRTL+8, you get a shot
of how the screen is in the reverse mode, And if you use the command
again, you return to normal view and so will the screenshot.

This means that any screenshop always will be related to the system
settings.

To invert negative pictures to positive or visa-versa, you must use an
application capable of inverting colors and objects to show these in the
reverted mode.

As I already have written, Photoshop can do this. But just discovered
that even GraphicConverter 6.4 is able to do the same...

Just open the negative picture in GC, chose 'Select All', go to menu
'Picture', go down to 'Invert'. There you get a lot of possibilities for
which purpose and from which type of picture the the picture is to be
inverted. - I just tried 'Normal' - et voila, the picture is now in
reverted color mode. - Again use 'Save As' to avoid spoiling the
original picture...

Cheers, Erik Rihcard

 

[AES]

I'm still hoping to learn from someone the technical explanation of why
a standard screen grab of an inverted image or window as seen on a Mac
screen, made using Grab after the screen display has been inverted using
Cmd-Option-Ctrl-8, is not captured or stored as the inverted image.

[In other words, Grab is NOT a WYSIWYG operation -- at least, not in the
attempts I've made.]

A screenshot of any kind will always follow the system and be 'as is' -
i.e. if the screen is inverted using the COM+ALT+CRTL+8, you get a shot
of how the screen is in the reverse mode, And if you use the command
again, you return to normal view and so will the screenshot.

This means that any screenshop always will be related to the system
settings.

Erik, somehow we're not seeing the same thing.

I've made a number of test screen captures using Grab, in situations
where ***the display screen was inverted at the time I dragged the
marquee tool around the region to be captured, or at the time I clicked
on the window to be captured with Grab's camera icon***.

I've then immediately Saved the captured_image.tiff image created by
Grab (which immediately appears on the desktop, looking inverted). I
then return my display screen to normal; open the "captured_image.tiff"
file in Preview or whatever; and this image file never appears as an
inverted image or seems to contain inverted image data.

If you have a detailed sequence of steps which can achieve an inverted
image file from a screen display that was uninverted in normal Safari
mode and has been inverted on screen with C-O-C-8, then captured using
Grab, I'd be glad to try it.

 

[Salmon Egg]

I'm still hoping to learn from someone the technical explanation of why
a standard screen grab of an inverted image or window as seen on a Mac
screen, made using Grab after the screen display has been inverted using
Cmd-Option-Ctrl-8, is not captured or stored as the inverted image.

[In other words, Grab is NOT a WYSIWYG operation -- at least, not in the
attempts I've made.]

If I remember from the old days (Macintosh Revealed and the Apple
"Telephone book" days), there was a window containing the data to be
displayed in memory. A system call was made to display which contained
all kinds of parameter to control how it was displayed using a handle
(pointer to a pointer) to this stored. This converted data was
transferred to the actual display memory without affecting the original.
My guess is that Grab and similar programs make a copy of the original
data and works on copy. Thus, only the parameters of the displaying
command change leaving the original data unchanged. There is a parameter
that says whether to invert on not invert the display.

Photoshop and similar programs will create an entirely new region in
memory to display. That will be inverted and displayed uninverted on the
screen.

I was actually able to use these system calls in those old days. Those
days seem to be over for me.

--

Sam

Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.

 

[Erik Richard Sørensen]

I'm still hoping to learn from someone the technical explanation of why
a standard screen grab of an inverted image or window as seen on a Mac
screen, made using Grab after the screen display has been inverted using
Cmd-Option-Ctrl-8, is not captured or stored as the inverted image.

[In other words, Grab is NOT a WYSIWYG operation -- at least, not in the
attempts I've made.]

A screenshot of any kind will always follow the system and be 'as is' -
i.e. if the screen is inverted using the COM+ALT+CRTL+8, you get a shot
of how the screen is in the reverse mode, And if you use the command
again, you return to normal view and so will the screenshot.

This means that any screenshot always will be related to the system
settings.

Erik, somehow we're not seeing the same thing.

I've made a number of test screen captures using Grab, in situations
where ***the display screen was inverted at the time I dragged the
marquee tool around the region to be captured, or at the time I clicked
on the window to be captured with Grab's camera icon***.

I've then immediately Saved the captured_image.tiff image created by
Grab (which immediately appears on the desktop, looking inverted). I
then return my display screen to normal; open the "captured_image.tiff"
file in Preview or whatever; and this image file never appears as an
inverted image or seems to contain inverted image data.

If you have a detailed sequence of steps which can achieve an inverted
image file from a screen display that was uninverted in normal Safari
mode and has been inverted on screen with C-O-C-8, then captured using
Grab, I'd be glad to try it.

I understand very well, what you're doing, but I simply can't get 10.5.8
to do anything like this. - Neither I have anything called something
like 'Grab.app', 'GrabTool' on my computers. If you're running 10.6.x it
might be a feature there which isn't in 10.5.x.

I've also tried to look into some of the hidden features in 10.5.x, but
there are no settings either that will enable this way of doing it...

Everytime I try all the screenshot combinations I always get the same
'Picture-x.jpg' file no matter which app opens the file(s). And I have
to use the invert tool in Photoshop - and now also GraphicConverter to
invert the colors.

Just for the record... I always use myh screens in reverse mode via
UniversalAccess so I have black background with white or light yellow
text - defined by the application I use. - This means that any picture
to me always is shown in inverted mode and I have to use the C-O-C-8
command to see pictures in normal view. So I only use normal view when
editing a picture - else always in reverse mode...

Cheers, Erik Richard