The big size images break my wordpress theme layout (exceeding in the width of publish). I've observed the Twenty Ten theme scale the big size images width very nicely (by reduction of the width and height). I wish to do same factor, how do i do this?

You have to add this to functions.php

add_theme_support( 'post-thumbnails' );

then you apply the more compact image inside your publish like:

the_post_thumbnail().

The default dimensions are 50/50, but you may either change that or increase the dimensions:

to alter default size you need to do

set_post_thumbnail_size();

and also to add dimensions you need to do

add_image_size( $name, $width, $height, $crop ); 

Wordpress then instantly produces multiple versions of the images within the different dimensions.

In later versions you will find already 3 dimensions, thumbnail, medium and enormous, that are being produced for you personally. To make use of these or any size added using add_image_size you just do:

get_the_post_thumbnail($post->ID, 'medium');        // to use the medium size, replace medium with whatever size.

To make use of pictures you clearly don't place the look in to the publish, you place them within the theme.

I discovered this post that provides a easy scale()-method that could be employed to do that.

However I would do that once the upload of the image is performed (inside your WordPress After sales) and save the thumbnail somewhere.

Also, WordPress should have the ability to do that out of the box.

Inside your stylesheet try something similar to:

img.size-large {max-width:960px !important}

Or, if you wish to pressure a particular width:

img.size-large {width:960px !important; height:auto !important}