String to image (quick)

Convert text string to RGB image (quickly) by using a dictionary of pre-generated images.

Two functions str2im and str2imq.

str2im: Convert text string to RGB image.

% str2im         %display example text
% str2im(str)      %text as char array or cellstr
% str2im(str,pad)    %margin: [N] or [H V] or [L R T B] as pixels or nan
% str2im(__,props)     %text property as value pairs, doc text
% I = str2im(__)         %return RGB image data as uint8
% [I,A] = str2im(__)       %return background alpha channel as uint8
% [I,A,H,W] = str2im(__)     %return image height and width
% 
%Remarks:
%-If a margin is nan then the background is cropped up to the text.
%-Slow because nothing is cached, a figure is generated for each call and
% print is used to generate the image (not getframe).
%-Maximum image size is limited by screen resolution.

Example:

clf,I=str2im({'str' '2im'},[10 8 -6 -5],'Color','b','Background','y','FontName','FixedWidth','FontWeight','bold')
clf,str2im('\phi_k^\pi',nan,'FontSize',200,'interpreter','tex')
clf,str2im('$$\int_0^2x^2\sin(x)dx$$',nan,'interpreter','latex')

Example: burn text into image

[I,A,H,W]=str2im(datestr(now),[0 0 -6 -3],'FontName','FixedWidth','Color','y','Background','k');
im=imread('peppers.png');x=size(im,2)-W;y=size(im,1)-H;im(y+(1:H),x+(1:W),:)=im(y+(1:H),x+(1:W),:)*0.6+I;imshow(im)

str2imq: Quickly convert text to image by making and using an image dictionary.

% str2imq([])      -clear the cache
% str2imq(L,P)       -cache text & properties
% D = str2imq()        -get dictionary
% I = str2imq(T,P)       -convert text to image using cache
% [I,A] = str2im(__)       -return alpha (see str2im)
% [I,A,H,W] = str2im(__)     -return height & width (see str2im)
%L: List of letters (char) or list string fragments (cellstr).
%P: Text padding & text properties (see str2im).
%D: Image dictionary of letters/string fragments (struct).
%T: Can also pointers at dictionary entries (integer vector).
%
%Remarks:
%-Dictionary images must have same height to concatenate horizontally.
%-Dictionary and text properties are cached as persistent variables.
%-Missing dictionary element will get appended on the fly (SLOW).
%-Text properties must be exactly same: property order, spelling, etc.

Example:

[I,A]=str2imq('Hello!','FontSize',80);   %fast repeat calls
imagesc(I,'AlphaData',A), axis off equal

Example: string fragments

imagesc(str2imq({'\pi' '\int' 'xyz'},'Interpreter','tex')), axis equal tight 

Example: clock

str2imq('0123456789:.',[0 0 0 0],'FontName','FixedWidth')         %init
while 1,imagesc(str2imq(datestr(now,'HH:MM:SS.FFF'))),drawnow,end %play