Good Day, Can we convert .txt to .jpg or .png

I want to save a text file as image(jpg or png) but the text contains data (some numbers). Is there any function like Imshow to convert from txt to jpg or png?

Thanks in advance

Answer 1

[DGM]

Besides insertText(), which is a CVT tool, and direct figure capture, there are other text-image tools on the File Exchange:

MIMT has both textim() and textblock(), which generate compact images of text in legacy hardware fonts. (CP437 based)

https://www.mathworks.com/matlabcentral/fileexchange/53786-image-manipulation-toolbox

http://mimtdocs.rf.gd/manual/html/textim.html

http://mimtdocs.rf.gd/manual/html/textblock.html

text2im() by Tobias Kiessling is similar, but only capable of a single font (the same default font used by MIMT textim()) (also CP437 based)

https://www.mathworks.com/matlabcentral/fileexchange/19896-convert-text-to-an-image

text2im by Rik offers a handful of modern font faces, though it supports a small charset and requires network connection.https://www.mathworks.com/matlabcentral/fileexchange/75021-text2im

text_to_image by Alec Jacobson is more flexible, but uses Imagemagick (external dependency), and is consequently slower.

https://www.mathworks.com/matlabcentral/fileexchange/49692-gptoolbox

There are also others:

https://www.mathworks.com/matlabcentral/fileexchange?q=text2im

And there are slightly different approaches:

https://www.mathworks.com/matlabcentral/fileexchange/38721-embed-text-and-graphics-in-an-image

Using MIMT textim():

mynumber = 1234;
A = textim(sprintf('my favorite password is %d',mynumber),'ibm-iso-16x9');
imwrite(A,'textpicture.png')

From here, the image can be resized (imresize()), padded (padarray() or MIMT addborder()), combined with other images. For compositing with another image, see this:

https://www.mathworks.com/matlabcentral/answers/101413-how-can-i-add-text-to-an-image-and-make-the-text-become-part-of-the-image-within-matlab#answer_747078

[Rayan Shaya]

Thank you for your time DGM, but my .txt file is a matrix (200*200) full of numbers so if I copy and paste them as a text in MyText='....' the code will crash. I have the results as a txt file inside matlab so I want to see if I directly convert it to an image, if not I can copy and paste the results outside matlab and get the image form. But all what I want is to get it directly from matlab. I tried the functions you sent but they didn't work as I want.

Thank you again

[DGM]

I'm going to stick with MIMT textim() here. I'm using a smaller array size for sake of web-readability, but this should work for any size array. I tailored the formatting to match the output that would be dumped to console when both "compact" and "short" format options are in use. Depending on the contents of your array, you may need to adjust the format string in the call to sprintf (e.g. to change field width, precision, or numeric type).

% this is your array. 
% if it's in a file, you'll have to read it using readmatrix() or something
myarray = rand(10);

% convert the array into formatted text in a cell array
% one line per cell
nl = size(myarray,1);
intext = cell(nl+1,1);
intext{1} = 'myarray =';
for r = 1:nl
    intext{r+1} = sprintf(repmat('%10.4f',[1 size(myarray,1)]),myarray(r,:).');
end

% rearrange the cell array of chars into a cell array of images
op = {};
for n = 1:nl+1
    op{n} = textim(intext{n},'hp-100x-8x6');
end

% edge-concatenate the images, add a 10px border
op = imstacker(op,'gravity','w','padding',0,'dim',1);
op = addborder(op,10);

imshow(op)

Of course, that's an extremely compact font. Using the prior ISO 16x9 font:

The results aren't likely going to be able to perfectly match the console appearance, as textim() doesn't offer whatever particular display font is being used by MATLAB.

Integer arrays

For an example of integer formatting:

myarray = randi([0 100],10);

% this sets the fieldwidth such that the columns are separated
% by no fewer than 3 spaces
maxdigits = floor(log10(max(myarray(:))))+1;
fs = sprintf('%%%dd',maxdigits+3);

nl = size(myarray,1);
intext = cell(nl+1,1);
intext{1} = 'myarray =';
for r = 1:nl
    intext{r+1} = sprintf(repmat(fs,[1 size(myarray,1)]),myarray(r,:).');
end

op = {};
for n = 1:nl+1
    op{n} = textim(intext{n},'hp-100x-8x6');
end
op = imstacker(op,'gravity','w','padding',0,'dim',1);
op = addborder(op,10);

imshow(op)

Array size considerations:

It's worth noting that for larger arrays, the results won't match console behavior, as the console wraps the output, whereas textim will not. Using the first code with the 8x6 compact font, a 200x200 array will create a 1628x12020 image. That's a pretty large image.

I assume there may be some motivation to reduce the image geometry required to represent the array content. Obviously, the image size also varies with the number formatting specified and the font being used. The smallest font available with textim() is 8x5, but it's not really intended to be very readable.

If the padding and label are not desired, and the field widths don't need to be fixed, some space can be saved by using variable-width columns with fixed spacing. Using the same 8x5 compact font as the prior image:

% columns values vary by order of magnitude
myarray = rand(10).*[1 1 1 10 10 10 100 100 1000 1000];

prec = 4; % number of decimal places
colspace = 1; % spaces between columns

% create format string for variable column widths
fs = '';
for c = 1:size(myarray,2)
    maxdigits = max(floor(log10(max(myarray(:,c))))+1,1);
    fs = [fs sprintf('%%%d.%df',maxdigits+prec+1+(c~=1)*colspace,prec)];
end

nl = size(myarray,1);
intext = cell(nl,1);
for r = 1:nl
    intext{r} = sprintf(fs,myarray(r,:).');
end

% same as before
op = {};
for n = 1:nl
    op{n} = textim(intext{n},'everex-me');
end
op = imstacker(op,'gravity','w','padding',0,'dim',1);

A similar approach can be used with integer formatting.

If formatting in columns isn't important and it suffices to just cram all the numbers into a box of some size, that's even simpler. Mat2str() will return the entire array as a single line of text. MIMT textblock() can flow that into a given geometry.

This flows the text into a rectangle of width between 300-400px. The exact width is selected automatically to optimize packing density. This uses default left-justification and does not break numbers.

myarray = rand(10);

textarray = mat2str(myarray,4);
tsize = [NaN 300 400]; % width optimization is optional; see docs
op = textblock(textarray,tsize,'font','everex-me','enablehyph',false);

Do the same thing, but allow lines to break anywhere.

op = textblock(textarray,tsize,'font','everex-me','hardbreak',true,'tightwidth',true,'enablehyph',false);

[DGM]

This is one row per line, close-packed integers.

Again, I'm using the unpublished 6x4 numeric-only font here. This font is not in the version of MIMT I put on the FEX. I attached a modified copy of textim.m and the font file if you want to use it. Just stick tinynum.mat in the MIMT/fonts directory and replace the MIMT textim.m with this one.

myarray = randi([0 9],10); % test data

% if you're reading from a file instead, use something like this
% fname = 'mytestfile.txt';
% myarray = readmatrix(fname,'delimiter',' '); 

s = size(myarray);
fs = ['%d' repmat(' %d',[1 s(2)-1])]; % only one space btw numbers
%fs = '%d'; % zero spaces btw numbers

op = cell(s(1),1);
for r = 1:s(1)
    thisrow = sprintf(fs,myarray(r,:).');
    op{r} = textim(thisrow,'tinynum');
end
op = imstacker(op,'gravity','w','padding',0,'dim',1);
op = op(1:end-1,1:end-1); % trim off 1px pad from character boundaries

imshow(op)

That's 200x200 single-digit positive integers with one space between numbers. Feel free to view that at full scale. It's clear and crisp, but the numbers are very small. The 8x5 and 8x6 fonts may be a readability improvement if the size increase is acceptable. Total image size is 1199x1595.

Repeating with a smaller array for sake of readability, this will work for positive integers

as well as for mixed positive and negative integers

though that obviously reduces the packing density

If you actually want all spaces removed, check the comments and use the alternative format string.

With these small fonts, I would avoid resizing the resultant image. With the 6x4 font, the image cannot be downscaled without becoming unreadable.

op = imresize(op,0.99); % only downscale just a tiny bit

Likewise, avoid saving the image as JPG.

I don't know how small you can manage to go with insertText() without it just turning into a blurry mess.

bg = zeros(15,100);
position = [0 0];
str = '1 2 3 4 5 6 7 8 9';
fontsize = 6;

op = insertText(bg,position,str,'textcolor','white', ...
    'boxcolor','black','fontsize',fontsize);
imshow(op)

EDIT:

For sake of absurdity, I've included another font and an updated version of textim. This gets the character size down to 5x4, but it's kind of a chore to read. I doubt it's practical level of readability, but you can play with it if you want. This is the same 10x10 random array:

[Rayan Shaya]

Thank you DGM,

After using this code the picture was generated perfectly but after zooming on the data I saw that the values are different from my text values.

And can we change the color of background from black to white? and the text's color from white to black?

Thank you in advance

[DGM]

How are they different? Are you using readmatrix() to read it, or are you using something else?

Can you provide an example file?

The image can be inverted easily enough

op = imcomplement(op);

or simply

op = 1-op;

since the image is of class 'double'.

[Rayan Shaya]

I am using readlines('mytextfile.txt')

I have some 1's and 0's in my text

myarray is readin a string of the same values as the values in my text file. But in the image it's showing me 4 8 9 digits not 1's and 0's.

in addition I don't have ('tinynumber') font I'm using ('hp-100x-8x6') Im not able to troubleshoot the code

Thanks for your time

[Walter Roberson]

char(44)

ans = ','

char(48)

ans = '0'

char(49)

ans = '1'

DGM's code assumes that you have an array of numbers, but when you readlines() you are getting an array of text containing '0', '1', and ',' and the numeric encodings for those characters are decimal 44, 48, and 49.

[Rayan Shaya]

This makes sense thank you Walter. Do you have any idea how can I solve it?

[Walter Roberson]

Under the circumstance that

myarray = readlines('mytextfile.txt');

then inside DGM's loop, replace

thisrow = sprintf(fs,myarray(r,:).');

with

thisrow = myarray{r};

[DGM]

Is it possible to use something other than readlines(), such that the imported array is numeric? I don't have readlines(), so I can't play with it, but I have a feeling that readmatrix() should work if readlines() does. If your file has redundant field separator characters (e.g. comma and space, or multiple spaces), it'll eat up a bunch of extra horizontal space unless you strrep() them in the string array returned by readlines().

If you want to use the 8x6 HP font, that's fine. That has good character shape for its size. If you wanted tinynum, I included it in the attachments above.

So long as it's just numbers, you could use any of the fonts. So long as the file import and string formatting works, the font shouldn't matter.

[Rayan Shaya]

Thank you guys it worked fine. I deleted the

thisrow = sprintf(fs,myarray(r,:).');

instead I wrote

thisrow=myarray(r,:);

since myarray is already a character array.

Thank you again guys!

Another question:

Is it possible to make the photos as GIFs? If I have many photos how can I create a GIF with them.

[DGM]

To create a single-frame GIF:

imwrite(myimage,'myimage.gif');

To create a multiframe (animated) GIF:

imwrite(myfirstframe,'myimage.gif','loopcount',Inf);
imwrite(mysecondframe,'myimage.gif','writemode','append');
% ... and so on

Of course, that's simplifying it a bit. In practice, you'll probably want to also specify 'delaytime' and other options as well. If your inputs are indexed, you'll have to include the map(s). If your frames vary in size, you'll have to deal with that as well. You'd probably want to just make sure they're all the same size.

There's also this for reading/writing multiframe GIF files:

https://www.mathworks.com/matlabcentral/fileexchange/52514-tools-to-read-and-write-animated-gif-files

Since that tool accepts inputs as 4D arrays, all frames must be the same size.

I don't know if you're intending to use this on the text images or actual photos like you said. Bear in mind the loss that must come with quantizing a photo down to a 256-color palette (shouldn't be a problem for black & white text though). Also consider that as far as I know, the current versions of imread() cannot correctly read multiframe GIF files any longer, so don't expect to open them back up and edit them.

[Rayan Shaya]

Hello DGM,

I am having an error using it.

[Walter Roberson]

You might need to use rgb2ind() to create a pseudocolor image and write that.

[DGM]

If the image is nominally grayscale, you can collapse it to a single-channel image with rgb2gray().

If the image has color content, you can use rgb2ind() to convert it to indexed color

[A map] = rgb2ind(A,numberofcolors);

or

[A map] = rgb2ind(A,colormap);

at which point, you'll have to provide imwrite with both the image and the map. Each frame may have its own unique map if desired.

[Walter Roberson]

@DGM

It turns out that imwrite() is not able to write GIF with a different colormap for each frame. Instead, it converts all frames to use the same colormap as the first frame.

GIF has been extended to allow different colormaps for each frame, but imwrite() does not support that.

[DGM]

Are you sure about that? The legacy behavior of imwrite() does allow unique local color tables to be written. The legacy behavior of imread() is to return all frames, but only the calculated color table for frame 1. It is required to use imfinfo() to retrieve the other color tables in order to get a valid image.

There have been changes to imread() in R2018b and sometime around R2021a which completely break multiframe GIF support. The first bug has a workaround; as far as I know, the second bug has none, as it also affects imfinfo().

https://www.mathworks.com/matlabcentral/answers/654298-nonsensical-imread-behavior-with-multiframe-gifs-in-r2019b

https://www.mathworks.com/matlabcentral/answers/893347-is-there-a-bug-in-imread-or-imfinfo-with-multiframe-gifs-in-r2021a-b

If they also broke imwrite() with these latest changes, I guess that's about what I've come to expect. Given that nobody else seems to care that their images are getting trashed, it'll probably stay that way. ... And yes, remapping all the frames to use the same color table is "broken".

[Walter Roberson]

@DGM

Hmmm... I thought I saw a Mathworks employee say that only a single color table was used. However when I test now

img = zeros(48, 64, 'uint8');
cmaps = [1 0 0; 0 1 0; 0 0 1];
filename = tempname + ".gif"
imwrite(img, cmaps(1,:), filename, 'writemode', 'overwrite', 'loop', inf)
imwrite(img, cmaps(2,:), filename, 'writemode', 'append')
imwrite(img, cmaps(3,:), filename, 'writemode', 'append')

[I, C] = imread(filename, 'frames', 'all');
whos
info = imfinfo(filename)
CT = info.ColorTable

although CT comes out as only suitable for the first frame, when I use my OS programs to examine the image fle, I do clearly see different color of frames, indicating that the local color tables must have been written properly.

[DGM]

Well I guess that's good to know. Since apparently imfinfo() can no longer read any color tables correctly, I didn't have an easy means to check that imwrite() was still working correctly when using the online tools to check the behavior in the newer versions.

Answer 2

[Walter Roberson]

MyText = 'Fly! Little white dove, fly!';

img = repmat(uint8(MyText), 20, 5, 3);

imshow(img)

But perhaps what you mean is more like

img = ones(30, 200, 3, 'uint8');
img = insertText(img, [1 1], MyText, 'TextColor', 'red', 'BoxColor', 'black');
imshow(img)

[Rayan Shaya]

Thank you for your time Walter, but my .txt file is a matrix (200*200) full of numbers so if I copy and paste them as a text in MyText='....' the code will crash. I have the results as a txt file inside matlab so I want to see if I directly convert it to an image, if not I can copy and paste the results outside matlab and get the image form. But all what I want is to get it directly from matlab.

Thank you again

[Walter Roberson]

MyText = readlines(filename);

insertText can handle multiple lines.

[Walter Roberson]

You have to zoom in a lot to read the image, because the image is going to be pretty big in order to hold all of the numbers. In this case, using these character size estimates, about 2000 pixels high and about 3200 pixels wide -- wider if your numbers need more digits.

40000 numbers is a lot to write into one image: you either have to have a large image or you have to write very very small.

%create a file of data to use for illustration
text_filename = fullfile(tempdir, 'example_data.txt');
example_data = randi([-9 9], 200, 200);
writematrix(example_data, text_filename, 'delimiter', ' ');

%demonstrate that it got written to the file correctly
cmd = sprintf('head -3 "%s"', text_filename);
system(cmd)

-4 0 -6 -1 2 0 9 -9 4 -9 -7 6 6 3 4 -6 1 -7 0 3 4 1 -7 -2 -5 9 -9 -5 7 1 -7 -6 7 -6 -6 -6 8 -3 -7 5 -6 -3 5 7 4 -3 -3 -9 -3 2 -7 9 -6 -1 3 -5 -3 5 -1 -7 1 2 -9 -2 3 -9 3 -8 0 3 9 2 -1 4 -2 7 5 0 -3 -3 1 4 2 6 -8 -5 9 -2 8 9 3 -6 3 7 -8 5 7 0 -9 -4 4 4 0 -6 8 3 0 8 -2 9 9 -3 -5 -9 -6 -1 -1 8 -7 2 7 -9 -4 9 -3 9 2 -7 -7 -6 4 0 -5 -4 6 7 -6 -6 7 -7 3 4 1 4 5 -4 -3 4 8 7 -3 -8 -1 5 -7 5 8 9 2 -8 -7 -2 8 6 -8 2 6 5 -6 -9 -8 -1 -1 5 -9 4 8 7 -2 -1 7 -4 -9 -9 4 -7 -6 -5 -3 3 -7 -5 1 4 3 7 -7 2 -1 5
-7 -6 5 1 5 9 -2 2 6 7 -9 2 9 2 7 8 -3 -3 2 7 6 9 2 9 0 -3 -6 7 -8 6 3 7 4 2 1 9 1 0 9 -3 -3 -2 9 -8 -3 6 -6 -1 2 6 -4 5 -5 4 9 -8 9 -6 -1 -8 5 3 -7 -5 6 9 8 8 1 -5 9 -4 -1 2 3 -6 0 6 0 3 8 1 -8 1 -7 -2 -2 0 -3 5 -1 -8 -6 -9 5 9 3 -9 2 1 -3 -7 -7 -2 -5 3 -4 6 4 4 1 6 2 -1 -5 4 4 -7 -5 0 -3 0 2 -2 0 7 9 3 2 0 -4 8 -7 6 6 -2 -2 8 4 -8 -4 -2 -5 -6 -7 7 0 9 -2 2 2 -5 -4 -8 1 -3 -9 -9 -1 -9 -5 -4 -9 2 -3 -1 8 0 1 4 4 -9 6 -3 -2 -7 9 1 5 3 9 -2 -8 2 -4 8 7 -4 -8 7 -5 -5 4 -9 6 2 2 2 6 2
8 6 1 9 -1 6 5 -6 1 -6 2 0 -7 4 5 7 -9 9 -8 5 0 4 7 8 -3 -6 5 -5 -5 -1 5 -6 2 4 -9 -8 -4 -2 -5 8 6 -9 -9 6 1 0 8 -8 2 -7 -9 3 8 3 9 -9 3 -4 7 -2 -3 -4 -1 -9 -3 1 4 7 4 -8 -1 6 -1 2 4 3 2 8 2 -9 -9 -9 -5 -6 -4 -6 4 -3 -5 5 -5 2 9 -3 6 -8 -5 7 -1 3 -8 -5 9 -3 6 -3 7 8 4 -1 1 -6 8 -3 -5 4 -7 -1 0 -2 -7 -3 0 5 -8 7 4 2 6 -7 -1 4 7 -2 -7 -6 7 -4 4 5 -9 4 5 6 6 -9 4 0 -6 6 -5 5 4 8 6 -6 -5 -7 7 3 2 5 -6 -7 9 7 6 7 9 9 9 7 -2 5 -7 -6 6 2 -7 -3 1 5 1 1 4 -4 -9 -4 2 -2 3 3 -1 -5 0 -6 -2 9 5 -9

ans = 0

%now the work

MyText = readlines(text_filename);
if isempty(MyText{end}); MyText(end) = []; end
num_lines = length(MyText);
maxlinelen = max(cellfun(@length, MyText));
fs = 8;
modifier = 0.53;
char_height = fs + 2;
char_width = modifier*fs + 2;
width_estimate = ceil(char_width * maxlinelen);
height_estimate = ceil(char_height * num_lines);
positions = ones(num_lines, 2);
positions(:,2) = 1 + (0:num_lines-1) * char_height;
img = zeros(height_estimate, width_estimate, 3, 'uint8');
img = insertText(img, positions, MyText, 'TextColor', 'red', 'BoxColor', 'black');

img_filename = fullfile(tempdir, 'example_image.png');
imwrite(img, img_filename);

size(img)

ans = 1×3

2000 3189 3

image(img)

[Rayan Shaya]

It worked fine thank you so much, but there is still a problem in the scaling of the image.

[DGM]

What is the problem? Is it too large? If so:

• Are there specific constraints on the geometry? (width restriction? height? both?)
• Are there specific requirements for formatting? (columnar format / one row per line / free format)
• What is the numeric formatting required? (floating point? integer? how many digits?)
• What is the smallest acceptable character size?
• Are you trying to resize the image itself with poor results?

As I mentioned, not even the console will display a 200x200 floating-point matrix in columnar format without breaking rows to fit the width. If you want an image that will fit the width of a screen or page at a readable scale, you are going to have to accept the limitations of the geometry.

To put this in perspective, if we assume a maximum image width of 1920px (a screen's width) and with a character size of 8x5px, the numbers (on average) can be no more than 1.9 digits wide, including the spaces between numbers. For example, the following image has 200 single-digit numbers.

For 5px wide digits and spaces, the result is 199*10+5 = 1995px wide.

If full alphanumeric support isn't needed, you can go down to about 6x4px without running into ambiguity. Using an unpublished numeric-only font, the same 200 number vector fits into 1596px.

That's pretty much the lower limit for a fixed-width font. At this scale, you'd better be using lossless file formats.

[Walter Roberson]

image_area_pixels = 1280 * 1024

image_area_pixels = 1310720

number_of_numbers = 200 * 200

number_of_numbers = 40000

average_pixels_per_number = image_area_pixels / number_of_numbers

average_pixels_per_number = 32.7680

height_ratio = 3/2;  %characters are taller than they are wide
syms character_width characters_per_number positive
number_width = character_width * characters_per_number

number_width = 

number_height = character_width * height_ratio

number_height = 

number_area = number_width * number_height

number_area = 

average_character_width = simplify(solve(number_area == average_pixels_per_number))

average_character_width = 

fplot(average_character_width, [1 10])
xlabel('characters per number')
ylabel('character width, pixels');

So if each number is one character wide, then if your characters are more than 4 pixels wide and 6 pixels tall, you cannot fit 200 x 200 in a single 1280 x 1024 image. If each number. A number that is 4 pixels wide is not readable.

[Rayan Shaya]

Thank you again guys for your time.

Answering DGM :

1) No specific constraint on the geometry, but I want to use all the matlab figure space if it can be done so it would be more effecient.

2) One row per line ( Take out all the spaces between columns and put them as a line)

That's why Im trying to read from my text file and use insertText() to write every line till I finish all the rows of my text file (using for loop) but I am not able to use insertText function correctly.

3) Integer and one digit (either 1 2 3 4 5...)

4) Doesn't matter incase it is still readable

5) I might resize it if I find it large enough, I can rescale it make it smaller

Answering Walter:

I have a question can't we know how many characters (digits in my case) every line can fit and how many rows; Like can I get the accepted hight and width of the figure using how many lines and how many carachters inside the lines

Hight*Width

how many lines (rows)* how many character in every line

I hope I made the question clear. I would really appretiate it if you can help and if not I'm really thankful that you helped me before.

Answer 3

[yanqi liu]

clc; clear all; close all;
figure;
% init edit
etf = uicontrol('Style','edit');
uicontrol(etf);
set(etf,'units','normalized','position',[0,0,1,1],'Max',10,'HorizontalAlignment','left','fontsize',14)
% txt 
txt = {' I want to save a text file as image(jpg or png) but the text contains data (some numbers)',...
    'Is there any function like Imshow to convert from txt to jpg or png?',...
    'Thanks in advance!'};
set(etf, 'String', txt);
% get image
f = getframe(gcf);
f = frame2im(f);
figure('Color','w'); imshow(f, []);
% save image
% imwrite(f,'res.png');

[Rayan Shaya]

Thank you for your time Yanqi, but my .txt file is a matrix (200*200) full of numbers so if I copy and paste them as a text in MyText='....' the code will crash. I have the results as a txt file inside matlab so I want to see if I directly convert it to an image, if not I can copy and paste the results outside matlab and get the image form. But all what I want is to get it directly from matlab.

Thank you again