I have the following image

Is there some way for me in Tikz, to remove the part to the right of the white line, and insert it with a slide of another image? Ideally I should be able to select 0-1 how far the image is to the right.

For instance with the following image,

the result could look like this

Sorry for no MWE, as I am very unsure where to start. Any help getting started would be much appreciated.

EDIT:

Thanks to Ignasis I was able to produce an MWE. The result looks like this

Improvements / Things I was not able to fix myself

• I was not able to include my original 8pyV9.jpg as this kept
  throwing me an Package graphics Error: Division by 0.?. Why? I tried to change the filename, alas nothing helped.




• Why is there a white margin on the bottom and to the right of the images? I would like them to be flush with the page borders.




• Is there a way to make sure the blue image fits the pagewidth, where the white line is correctly placed? I was able to set it correctly manually now, but if I change the page borders, it throws everything off.




• Is it possible to move the right image right and left to choose which parts is included?

MWE

documentclassarticle
usepackagetikz

usepackage[b5paper,lmargin=25mm, rmargin=25mm,tmargin=27mm, bmargin=30mm]geometry

usepackagegraphics,graphicx,calc
 definecolormainHTML003349

begindocument

pagestyleempty

newgeometrymargin=0pt

defmygraphicincludegraphics[width=textwidth]Q7xB7.png
newlengthgraphicheight
setlengthgraphicheightheightofmygraphic

vspace*fillnoindent%
begintikzpicture
 %
 beginscope
 path[clip] (18,0)--++(180:6.7cm)--++(70:graphicheight)-|cycle;
 node[anchor=south east] at (18,0) includegraphics[height=graphicheight]uniwallpaper.jpeg;
 % fill[color=main,opacity=0.8] (0,0) rectangle (textwidth,graphicheight);
 endscope
 beginscope
 path[clip] (0,0)--++(0:11.2cm)--++(70:graphicheight)-|cycle;
 node[anchor=south west] includegraphics[width=textwidth]Q7xB7.png;
 endscope
endtikzpicture

enddocument

This is very similar to the other two answers with the main difference being that I install a local coordinate system on the pic to make things more convenient. You still need to find out the coordinates by looking, but now the clip path becomes

clip (0.6345,0) -- (0.963,1) -| (1,0) -- cycle;

where the coordinates are such that (0,0) is the lower left and (1,1) the upper right corner of the "reference" picture. This way you do not have to put in explicit dimensions.

documentclassarticle
usepackagetikz
usetikzlibrarycalc
usepackage[b5paper,lmargin=25mm, rmargin=25mm,tmargin=27mm, bmargin=30mm]geometry
begindocument
begintikzpicture[nodes=inner sep=0pt,anchor=south west]
 node (X) includegraphics[width=textwidth]picA;
 beginscope[x=(X.south east),y=(X.north west)]
 beginscope
 clip (0.6345,0) -- (0.963,1) -| (1,0) -- cycle;
 path let p1=(X.north east) in (0,0) 
 nodeincludegraphics[width=x1,height=y1]picB;
 endscope
 endscope
endtikzpicture
enddocument

To expand on Ulrike's comment, here is a quick and dirty example on how to clip an external image that is directly taken from the pgf manual

documentclass[12pt,a4paper]article
usepackagegraphicx,tikz
begindocument
begintikzpicture[path image/.style=
path picture=
node at (path picture bounding box.center) 
includegraphics[height=3cm]#1
;]
draw [path image=example-image-b,thick](0,1) -- (0,3) -- (1.5, 1.5) -- (1,1) -- cycle;
endtikzpicture
enddocument

Then you can superimpose two images, once having clipped one.

Another solution clipping images included as nodes:

documentclass[tikz,border=2mm]standalone
begindocument
begintikzpicture
beginscope
path[clip] (0,0)--++(0:3.5cm)--++(75:3cm)-|cycle;
node[anchor=south west] includegraphics[width=6cm]Q7xB7;
endscope
beginscope
path[clip] (6,0)--++(180:2.3cm)--++(75:3cm)-|cycle;
node[anchor=south east] at (6,0) includegraphics[height=3cm]8pyV9;
endscope
endtikzpicture
enddocument

Update

If you want to cover some part of the page with this picture, it's better to use absolut positioning, which can be done with remember picture and overlay options and using the current page node. You need to compile twice before getting the correct result.

The white space around the figure was due to inner sep which keeps a certain distance between node contents and border. With inner sep=0pt, there is no space.

Finally you can use bb ("bounding box") option from graphicx package to select which part of the included figure is shown: bb=0 0 1400 702 means take the rectangle from (0,0) to (1400,702) points (Postscript points not pixels). I think you'll have to test to find the desired fragment.

documentclassarticle
usepackagetikz
usepackage[b5paper, lmargin=25mm, rmargin=25mm, tmargin=27mm, bmargin=30mm]geometry

%usepackagegraphics,graphicx,calc
usepackagecalc
definecolormainHTML003349
pagestyleempty

defmygraphicincludegraphics[width=paperwidth]Q7xB7.png
newlengthgraphicheight
setlengthgraphicheightheightofmygraphic

begindocument

begintikzpicture[overlay, remember picture]
 %
 beginscope
 path[clip] (current page.south west)--++(0:10.8cm)--++(70:graphicheight)-|cycle;
 node[anchor=south west, inner sep=0pt] at (current page.south west) mygraphic;
 endscope%
 beginscope
 path[clip] (current page.south east)--++(180:6.7cm)--++(70:graphicheight)-|cycle;
 node[anchor=south east, inner sep=0pt] at (current page.south east) includegraphics[height=graphicheight, bb=0 0 1400 702, clip]8pyV9;
 endscope
endtikzpicture

enddocument