Rescaling to actual size

[Decdublin]

I have photographed a series of drawings I have included in each a measure rule, I now want to out put these images at actual size ( this used to be so easy in the darkroom) anybody know an easy way to do this in Photoshop or lightroom. The method I've used before is to estimate the size and export it frol LR at that, then make a new file size 12" ( my rule size ), drag this onto my image, make a copy layer of the original b/g then free transform until the rule is the same size as the 'new file' there hast to be a better way??? Anyone??

 

[jon ryan]

Have you tried entering the sizes you need when using the crop tool in Photoshop? This will give the exact dimension of the resultant print.

 

[Decdublin]

Hi Jon

I am not trying to set the size of the print, I want the size of the print to be elastic. Imagine shooting a painting that you know is 10" wide then your solution makes sense, you just make the crop width 10" and crop to the edge of the painting. Now imagine you have an image of a painting of unknown dimension but included is a 12" ruler, I want to scale the print so that the ruler in the image prints actual size. how i do it at the moment is described above but I wonder is there an easier way?

 

[Kerioak]

Hi Declan, the way you are doing it is the way I would probably do it once the photos are on the computer.

Can you have the ruler next to the drawing, focus until the ruler fills one edge of the camera viewfinder and do it as you take the picture. Might need a bit of experimenting to get the exact distance as what you see and get can vary depending on the viewfinder/wearing glasses etc etc.

 

[leftcurl]

can't you measure the ruler on screen using the ruler in PS. Then, let's say the 12" ruler is 61mm on screen, then that's a ratio of 1:5 (based on 12" = 305mm).

So just resize the image to the same ratio and hey presto? or no presto? :shrug:

 

[Paul MR]

There is no easy way of doing it, measuring the screen is not going to work as you would have to work out the screen resolution, document resolution with the document at 100 percecnt. It gets very messy.
The way it can be done is to draw a Path using the shape line tool.
This path being the 12" rule in the picture. Then running the follow script to resize.
I wrote this for some archaeologists as their pictures had a 5cm measurement.
It's been amended for 12"
Hope it's of use.

main();
function main(){
if(!documents.length) return;
if(!activeDocument.pathItems.length) return;
// with a line shape layer active and no other paths in the document 
var line = measureLine(activeDocument.pathItems[0]); 
activeDocument.pathItems[0].remove();
var ratio = (((activeDocument.resolution)*12) / Number(line[2]))*100;
activeDocument.resizeImage (new UnitValue(ratio,'%'), new UnitValue(ratio,'%'), undefined, ResampleMethod.BICUBIC);
}
function measureLine(path){ 
   var res = new Array; 
   var lineStart = path.subPathItems[0].pathPoints[0].anchor; 
   res.push( lineStart ); 
   var lineEnd = path.subPathItems[0].pathPoints[3].anchor; 
   res.push( lineEnd ); 
   var a = Math.max(lineStart[0],lineEnd[0])-Math.min(lineStart[0],lineEnd[0]); 
   var o = Math.max(lineStart[1],lineEnd[1])-Math.min(lineStart[1],lineEnd[1]); 
   var c = Math.sqrt((a*a)+(o*o)); 
   res.push(c); 
   var ang = (180/Math.PI) * Math.atan2(o,a); 
   if(lineStart[1] < lineEnd[1]){
      ang = -ang; 
   }; 
   res.push(ang); 
   return res; 
}