least blurred image

[maurot43944773]

Hi all, I have Adobe Photoshop 21.0.2 and a problem.

I have a set of images (of the same thing, let's say a page with handwritten text), and these images can have a certain degree of blurriness. I wonder if there's a way for Photoshop to tell me which image is the least blurred.

[Stephen_A_Marsh]

Two options that spring to mind...

* Compare histogram values at 100% view for the image with the higher Std. Dev. value which will be "sharper" (ensure that the histogram is refreshed, uncached)

* Use Adobe Bridge and your eyes with the loupe tool (no, I'm not being sarcastic)

A third option would be to use shake reduction to examine the PSF "blur estimation region" preview manually for the same selected region for each image.

[maurot43944773]

Thank you for your answer.
In this way, however, I should make the choice of the better image, and I,
being human, am fallacious. It would be way better if it was a task for PS
to do by itself.
Can this be a feature I could ask?

[Stephen_A_Marsh]

You can make a feature request here:

Submit product feedback

For now, I can envision a script where you would select a folder of input images and a text file would be output listing the source filename and the standard deviation value for each file.

[maurot43944773]

I've studied the problem, and it seems the solution lies in making a grayscale of each image, an histogram equalization, followed by a convolution of some sort (or more than one, aggregated with an euclidean norm, or a mean) -- it seems there are more than one kernel that can be applied --, then selecting the maximum value of the variance, and then selecting the image with the maximum among these values.

I don't know if everything can be done via a script (output a number from an image as input?).

Thank you for your support!

[Kionte22986433g0dl]

Greetings, Im new at scripting... Will this method move the most OOF (Out of Focus) Image to a separate folder or vice versa? 

[Stephen_A_Marsh]

@Kionte22986433g0dl 

If you are referring to the script that I posted, then the description says it all:

The following script will process a top level directory and write out a .csv file to the desktop with the standard deviation value for each image. The highest Std. Dev. value will be the "sharpest" image. 

---

So no, it does not move images, it writes a spreadsheet file to "log"  each image. The Standard Deviation value can be sorted in the spreadsheet.

[c.pfaffenbichler]

Have you read »Depth of field blending« here? 

Combine images with Auto-Blend Layers

[maurot43944773]

Hi! thank you for your answer. What should I look for in this document?

[c.pfaffenbichler]

»Depth of field blending«? 

[maurot43944773]

I really can't understand what combining images has to do with my question.

[Chuck Uebele]

I was thinking along the same line. By using depth of blending of focus stacking, Photoshop will combine the sharpest parts of each image. At least it should in theory. With that type of image, PS might have difficulty detecting which parts are sharpest due to large areas with little detail.

[maurot43944773]

Ok, now I think I understand. But that's not what I've asked.

I don't want a costructed image, I would like to know which one is the best.

[c.pfaffenbichler]

»I don't want a costructed image, I would like to know which one is the best.«

What is the point of this in your process? 

@Stephen_A_Marsh  already provided a Histogram approach, one could automate that with Scripting. 

[maurot43944773]

I don't want a constructed composite image because it can lead to artifacts, missing parts, or irregular areas (one taken from an image, another from another, ...). Since I have to photograph a document I would like to have an intact "original" image. I don't know if I've made myself clear.

[D Fosse]

If you view at 100% and can't immediately decide which is sharpest, then they are equally sharp. Don't overcomplicate this 😉

[maurot43944773]

Each image is 2976×3968, and I have more than 1500 images (each document repeated 5-6 times). If I have to look each one of them I'll surely die 😛

[Stephen_A_Marsh]

I was hoping to stand on the shoulders of gaints, however, finding a working script to get the Standard Deviation is proving to be difficult:

How to get the histogram's Std Dev

[Stephen_A_Marsh · Accepted solution]

The following script will process a top level directory and write out a .csv file to the desktop with the standard deviation value for each image. The highest Std. Dev. value will be the "sharpest" image.

/* 
least blurred image
https://community.adobe.com/t5/photoshop/least-blurred-image/m-p/12183817

Recursive processing to CSV code based on:
https://forums.adobe.com/message/9697558#9697558

Standard deviation histogram processing code based on:
https://community.adobe.com/t5/photoshop/how-to-get-the-histogram-s-std-dev/td-p/9875041
*/

#target photoshop;
app.bringToFront();

main();

function main() {
    var inputFolder = Folder.selectDialog("Select the folder to process:");
    if (inputFolder === null) return;

    // Add or remove file extensions as required
    var fileList = inputFolder.getFiles(/\.(jpg|dng|tif|psd|crw|cr2|psb|exr|nef|dcr|dc2|erf|raf|orf|tga|mrw|mos|srf|pic|pct|pxr|pdd|pef|png|x3f|rw2)$/i);

    var outputFile = File("~/Desktop/" + decodeURI(inputFolder.name) + ".csv");
    outputFile.open('w');
    outputFile.writeln('Filename,Highest Std. Dev. Value = "Sharpest" Image');

    for (var a in fileList) {

        open(fileList[a]);

        ///////////////////////////////////

        /* 
        How to get the histogram's Std Dev
        https://community.adobe.com/t5/photoshop/how-to-get-the-histogram-s-std-dev/td-p/9875041
        Credit to c.pfaffenbichler for the 2018 code and thanks to Kukurykus for the 2021 update!
        */
        if (app.documents.length > 0 && app.activeDocument.mode == DocumentMode.RGB) {
            var theR = histogramMeanStandardDeviation(app.activeDocument.channels[0].histogram);
            var theG = histogramMeanStandardDeviation(app.activeDocument.channels[1].histogram);
            var theB = histogramMeanStandardDeviation(app.activeDocument.channels[2].histogram);
            var theStdDev = (((theR[2] + theG[2] + theB[2]) / 3).toFixed(2));
            // Write the filename and values
            outputFile.writeln(decodeURI(activeDocument.name) + "," + theStdDev);

        }

        ////// get mean of histogram //////
        function histogramMeanStandardDeviation(theHist) {
            // get total number;
            var thePixels = 0;
            for (var m = 0; m < theHist.length; m++) {
                thePixels = thePixels + theHist[m];
            }

            // get mean and median;
            var theMean = 0;
            var aTotal = 0;
            var check = false;
            for (var n = 0; n < theHist.length; n++) {
                theMean = theMean + (n * theHist[n] / thePixels);
                aTotal = aTotal + theHist[n];
                if (aTotal >= thePixels / 2 && check === false) {
                    theMedian = n;
                    check = true;
                }
            }

            // get standard deviation;
            var theStandDev = 0;
            for (var o = 0; o < theHist.length; o++) {
                theStandDev = theStandDev + (Math.pow((o - theMean), 2) * theHist[o]);
            }
            theStandDev = Math.sqrt(theStandDev / thePixels);
            //
            return ([theMean, theMedian, theStandDev]);
        }

        ///////////////////////////////////

        app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);
    }

    outputFile.close();
    app.beep();
    alert("CSV created:" + "\n" + decodeURI(outputFile));
}

[Stephen_A_Marsh]

@maurot43944773 – so, how did the script work for you?

[maurot43944773]

Thank you so much for the script. I didn't know such a thing was possible.

For now I solved my problem by a simple java application that reads all the images in a folder and tell me which one is the sharpest. I though it was faster to load and process than opening PS, load/process all the images, extracting a value from each one, and select the greatest.

[Kukurykus]

Could do you please do two things:

- share an image you use to test above script with

- mark the given answer as the correct solution 😉

[Stephen_A_Marsh]

What Java app? ImageJ? Something else? What method does it use to determine the sharpest image? Can you share links for more info?

Does the Java app's "sharpest image" agree with the Photoshop scripts highest Std. Dev. value?

[maurot43944773]

It's a simple console java app (LeastBlurredImage).

I found several kernels that can be applied to the image.

The solution lies in making a grayscale of each image, an histogram equalization, followed by a convolution with a kernel, then selecting the maximum value of the variance, and then selecting the image with the maximum among these values.

The images are along the lines of deed 15600301 - Copy:

[Kionte22986433g0dl]

Did you ever find out what method work best for you? i am currently working in the way way that you wre then and is now looking for a solution to detect soft/out of focus images