Avec The GIMP, il y a toujours moyen...

Emmanuel Florac l'a dit, lui, il fait tout avec the GIMP! Alors, une fois
qu'on a retenu l'expression anglaise "aspect ratio" (je ne connais pas
l'équivalent français), on peut faire une recherche chez Google, Voici ce
qu'on trouve comme premier lien:

http://www.gimpguru.org/AskTheGuru/G20050312/

Ask The Guru

Cropping with an Aspect Ratio in the GIMP

First I just want to say again how glad I am to find this group. I have to
say everyone here is extremely helpful and it's very much appreciated.

Being a user of Photoshop in the past, I really got used to a function for
cropping...and I would like to know how to duplicate it in GIMP.
Basically, when I would click on the crop tool in PS, a toolbar would show
up and give you a list of various sized to crop the photo to, and when you
dragged the crop tool over the image, you could make it crop where you
wanted AND be the size you wanted. You could also set the dpi in this same
toolbar.

I am sure I am just not understanding how to do this in GIMP, and would
appreciate it if anyone would be so kind as to explain it. I am not a
technical type at all, so all that stuff about x and y confuses me when I
try to crop with GIMP. I have other questions, but I will save those for
another time. Thank you again.

Lisa..who currently uses GIMP to edit digital photos of my 2 year old
daughter =)



Hi Lisa,

What you are talking about is setting a particular aspect ratio when you
crop. This is done fairly straightforwardly in the GIMP, albeit perhaps
not as simply as with the toolbar feature you describe. Here's one way to
do it...

Original photo. I'd like to make a 4x6 inch print (fairly standard print
size at any US photofinisher) of a crop from it.

Choose the rectangular selection tool (keyboard: R) or ().

If you want to crop to a certain print size (e.g. 4x6 in) or a certain
aspect ratio (e.g. 2:3; same as 4x6) then in the Tool Options dialog,
choose "Fixed aspect ratio" from the drop down dialog. Don't choose "Fixed
size" even if that is what you think you want.

In the Width and Height fields, enter the numbers for your desired aspect
ratio. A 35mm film frame is 24mm x 36mm, so it has an aspect ratio of 2:3.
This corresponds to common print sizes of 3.5 x 5 in (approx) and 4 x 6.
An 8 x 10 print is related to the 4:5 aspect ratio of large format film,
while 7x5 is closer to the 4:3 aspect ratio used by most digicams today.

You can set the units field appropriate for your numbers (e.g. in this
case I set it to "in", since I want a 4x6 inch print), although I don't
think it's that important at this stage.

You do need to enter whole numbers, so round up to the nearest whole
number aspect ratio.


Click and drag in the image window to marquee your selection. Zoom in a
bit first if you like (as I did here). Don't worry about getting the
framing too precise, it is just a starting point. You should notice that
the drag selection is constrained to your fixed aspect ratio. If you make
a mistake just clear the selection (Shift+Ctrl+A) and drag again to make a
different selection.

Some handy keyboard shortcuts at this stage are:

* +/-: zooms in and out
* Ctrl + Shift + A: clear the current selection
* Alt + Up/Down/Left/Right arrow: nudges the entire selection in the
direction you are choosing
* Alt + Shift + Up/Down/Left/Right arrow: bumps the entire selection
in the direction you are choosing

Once the selection is approximately where you want it, choose the Crop
tool (keyboard: Shift+C) or () and click on the image.


In the Crop & Resize Information dialog, click the "From Selection"
button. The crop lines will be set to your selection made in the previous
step. Now press Shift+Ctrl+A to clear the selection.

Now you can fine tune the crop. Some handy keyboard shortcuts are:

* +/-: zooms in and out
* Alt + Up/Down/Left/Right arrow: nudges the entire crop in the
direction you are choosing
* Alt + Shift + Up/Down/Left/Right arrow: bumps the entire crop in
the direction you are choosing

You can also use the mouse to enlarge or reduce the crop from any corner
at this point, but be sure to hold down the SHIFT key or it won't keep
the aspect ratio.

Once you've got the crop lines positioned exactly as you want them, click
the "Crop" button in the Crop dialog.

Don't click Resize as this will only crop the pixels outside the crop
lines but leave the canvas at the original size.

If you make a mistake, just Undo (Ctrl+Z) and try again.



Finally, set the print size (Image/Print Size) and set the width and
height to the desired size. The dimensions should be compatible with your
aspect ratio chosen in step 1 and you also probably want to make sure that
the resolution (in PPI) is sufficient for a good, sharp print. In this
case I chose to go with 3.5 x 5.25 which is the same 2:3 aspect ratio as 4
x 6. At 3.5 x 5.25 I'm getting close to 240 PPI which is quite sufficient
for a very sharp print.

-------------------------------

Ça vous a fait plaisir de connaître Lisa? Voici maintenant les
instructions pour PaintShopPro. Pas besoin de choisir, déchoisir et
rechoisir des options dans des menus qui vont se refermer illico sous
votre nez:

"Tu presses CTRL, puis tu tires le coin, glandu. Les dimensions des deux
côtés et leur rapport sont au bas de l'écran."

Évidemment, les gens comme Emmanuel Florac trouvent que ça ne fait pas
professionel du tout. Le mode graphique, ils aiment pas. Depuis le temps
du DOS qu'ils ne trouvent pas ça efficace. Ils aiment mieux lire des
instructions et passer leur temps à fouiller dans les menus. Ils en ont du
temps!

Les graphistes? Pas tant que ça... Le client attend et il veut ses
épreuves pour hier.

Maintenant, M. Florac va nous expliquer les avantages de Ubuntu par
rapport à Solaris.