Making an HTML table of pixel values with colored cells

Today's post shows you how to make a table with image colors and pixels appear when you publish your MATLAB scripts to HTML using the publish function. The result looks like this:

rgb = imread('peppers.png');
disp(im2html(rgb(88:92,200:204,:)))

R:80 G:50 B:77	R:78 G:47 B:74	R:76 G:47 B:71	R:95 G:65 B:73	R:158 G:129 B:117
R:76 G:47 B:77	R:75 G:46 B:71	R:91 G:63 B:72	R:158 G:130 B:119	R:192 G:165 B:141
R:77 G:45 B:70	R:82 G:51 B:63	R:148 G:120 B:114	R:192 G:166 B:146	R:203 G:176 B:153
R:75 G:43 B:65	R:126 G: 95 B: 97	R:186 G:160 B:145	R:197 G:173 B:154	R:208 G:180 B:160
R:100 G: 70 B: 72	R:174 G:146 B:135	R:193 G:169 B:151	R:198 G:175 B:158	R:211 G:189 B:170

I was inspired to do something like this when I saw Printing Variables to HTML Tables in Published Code (by Ned) on the File Exchange a while back. It also produces an HTML table with colored cells and superimposed values. Here's a sample:

I was also thinking about the Pixel Region Tool in the Image Processing Toolbox. Here's a screen shot:

I wanted to go a bit further than Ned's original. I wanted to handle all the different kinds of image types (grayscale, truecolor, indexed with direct mapping, indexed with scaled mapping). I also wanted to replicate the feature of the Pixel Region Tool that automatically changed the color of the superimposed text depending on whether the underlying pixel was dark or light. (You can see that effect in the screen shot above.)

I've packaged all this in a function called im2html. You can download this function from the File Exchange.

Here are some examples showing how to use im2html with different types of images.

Display a table of values for a gray-scale image:

I = imread('pout.tif');
disp(im2html(I(125:134, 104:114)))

112	112	107	97	91	87	86	84	83	84	84
120	126	128	128	114	101	87	87	86	86	87
116	132	138	142	142	132	98	91	89	87	89
110	133	145	150	149	147	121	101	93	93	91
109	133	145	156	159	153	142	130	109	102	99
109	131	143	154	169	171	169	169	154	139	137
108	126	142	151	169	175	186	190	189	180	179
110	121	137	148	158	167	177	187	199	189	185
112	117	136	146	151	159	159	163	189	189	180
114	113	132	142	147	151	156	154	162	184	179

I = magic(10);
disp(im2html(I,[]))

92	99	1	8	15	67	74	51	58	40
98	80	7	14	16	73	55	57	64	41
4	81	88	20	22	54	56	63	70	47
85	87	19	21	3	60	62	69	71	28
86	93	25	2	9	61	68	75	52	34
17	24	76	83	90	42	49	26	33	65
23	5	82	89	91	48	30	32	39	66
79	6	13	95	97	29	31	38	45	72
10	12	94	96	78	35	37	44	46	53
11	18	100	77	84	36	43	50	27	59

Display a table of values from an indexed image:

[X,map] = imread('trees.tif');
disp(im2html(X(156:160,244:248),map))

<93> R:0.42 G:0.68 B:0.87	<93> R:0.42 G:0.68 B:0.87	<82> R:0.35 G:0.65 B:0.81	<77> R:0.39 G:0.61 B:0.81	<93> R:0.42 G:0.68 B:0.87
<82> R:0.35 G:0.65 B:0.81	<45> R:0.22 G:0.45 B:0.68	<50> R:0.42 G:0.42 B:0.52	<82> R:0.35 G:0.65 B:0.81	<82> R:0.35 G:0.65 B:0.81
<93> R:0.42 G:0.68 B:0.87	<50> R:0.42 G:0.42 B:0.52	<32> R:0.39 G:0.29 B:0.55	<44> R:0.52 G:0.32 B:0.52	<93> R:0.42 G:0.68 B:0.87
<93> R:0.42 G:0.68 B:0.87	<93> R:0.42 G:0.68 B:0.87	<44> R:0.52 G:0.32 B:0.52	<20> R:0.58 G:0.13 B:0.29	<27> R:0.45 G:0.22 B:0.42
<105> R:0.55 G:0.74 B:0.91	<93> R:0.42 G:0.68 B:0.87	<77> R:0.39 G:0.61 B:0.81	<44> R:0.52 G:0.32 B:0.52	<20> R:0.58 G:0.13 B:0.29

You can also capture the output of im2html as a string, or write it directly to a file.

s = im2html(magic(10),[]);

im2html(magic(10),[],'OutputFile','magic_table.html')

Give im2html a try. Comment here (or on the File Exchange page) if you find a good use for it, or if you have ideas about making it better.

Next time I'll go into some of the details about how im2html works, including the use of raw HTML in your publishable MATLAB scripts, as well as an obscure thing in the Image Processing Toolbox called imagemodel.

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Published with MATLAB® 7.14

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owr replied on June 6th, 2012 at 13:05 UTC :

Hi Steve,

Thanks for your (timely) submission. I am currently working on a project that requires this sort of thing. I am using Ned’s “makeHtmlTable” as it is more appropriate for my needs (I am not displaying images) but have noticed that the table rendering does not work for me in 2012A, though it does in 2011A. Instead of the colored table you get with the call in your example to “magic(11)”, I get unformatted text. Are you using any special publish configurations to get it to work for you in this blog post? Inspection of the source shows that there has been changes between the html generated in 2012a and 2011a, though I havent dug in enough to figure out what is causing the rendering discrepancies. I am just wondering if this is something you have encountered and overcome.

Thanks for your time.

owr replied on June 7th, 2012 at 11:54 UTC :

After a little investigation, I can answer my own question – maybe it will help someone else.

In 2012A the autogenerated HTML on my computer (64 bit Windows 7) is including default declarations for quite a few selectors compared to 2011A. These include table, tr, td, th. The result is that html tables generated by many of the ML utilities Ive found on the File Exchange do not render “properly”. It looks like the examples generated in this blog were done with 2012A, so apparently this isnt the same for every computer? Perhaps it depends on default settings. I was able to work around it by including html in my script to link to a custom style sheet. It would be nice if publish configurations allowed one to link directly to a css file (and remove the default settings rather than just over-ride them manually) in addition to xsl.

Steve Eddins replied on June 8th, 2012 at 13:43 UTC :

Owr—Thanks.

Steve on Image Processing

June 2nd, 2012

Making an HTML table of pixel values with colored cells

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