How to create a bitmap?

[Prashant]

Hi,

I have a huge problem. I have a data file which looks something like
this -:
..1 .5 .9 -1 .2 .5 ......
..2 .9 .1 .4 .3 -1 ......
..2 .4 .5 .7 .6 .2 ......
........
........

Now I have to create a bitmap out of this using C++ and I really dont
know how to do it? Could someone please tell me a way to go about this
or atleast point me in the right direction?

Thanks,
Prashant

[Thomas Matthews]

Prashant wrote:

Hi,

I have a huge problem. I have a data file which looks something like
this -:
.1 .5 .9 -1 .2 .5 ......
.2 .9 .1 .4 .3 -1 ......
.2 .4 .5 .7 .6 .2 ......
.......
.......

Now I have to create a bitmap out of this using C++ and I really dont
know how to do it? Could someone please tell me a way to go about this
or atleast point me in the right direction?

Thanks,
Prashant

For your data, I believe that a graph would suffice better
than a bitmap. For advice on how to draw a graph, search
the web for libraries or consult newsgroups on graphics,
programming or your platform.

This data could be interpreted as a matrix of pixels, but
_you_ would have to decide on how to map the values to
pixel colors or shades of gray.

--
Thomas Matthews

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[assaarpa]

> Personally, I've never heard of a floating-point bitmap before. Every

I have. Those are used all the time, personally I don't discriminate between
floating-point and integer pixelformats being relevant or not. For example
OpenEXR format is a HDR fileformat which supports 16-bit and 32-bit floating
point color and arbitrary data channels. Also, if you do GPU specific work
you will find out that grayscale or otherwise mono-channel floating-points
are used frequently, this is true for both OpenGL and DX 9.0c specific work.
It's not uncommon at all.

bitmap I've ever worked with (and that's a lot) uses some form of integer or combination of integers (such as three integer: R,G, and B). In any case,
Those are very common ones for the reason that most hardware for
workstations and Windows follow de-facto conventions so that they play the
ball with the standard API's like X and GDI. If you look into OpenGL 1.5 /
2.0 and DirectX 9.0c you might notice that in the recent years a lot of
formats have been standardized so that applications can do HDR imaging in
wider range of hardware with smaller investment in development times.
I'd bet the farm (well, the back forty, anyway), that the OP wanted to know how to create a specific type of bitmap (such as a CBitmap object in VC++ or something similar), which is exactly what makes the query off-topic here.
I'm sure he can ask the question and we can then turn him down if it is
off-topic, so far it has been on-topic. This bickering and second guessing
him has been more off-topic than his question.
I am curious as to the OP's data. Whatever is eventually used to actually
display that data as a bitmap (in the common graphical sense), some kind of mapping function is going to be needed to determine what those values are
intended to represent. For example, is the -1 supposed to mean black (no
color), or what? So he's really got two problems. First, how is the data
The input could be anything, it don't necessarily have to be color. I do
store normal maps, displacement and other data in bitmap objects. For
example in the case of displacement data I will only have one channel active
and I will tag it as "luminance" , even though it is just some arbitrary
scalar data. This is a very common practise with vertex- and fragment
programming, the fragment program for example discriminates between
different channels using default names for them even if the program doesn't
ultimately write the channel into respective output fragment's channel. Big
deal.

I see he has a floating point matrix of data and wants to do SOMETHING with
it. So far he asked how to put it into bitmap, I am not sure if his problem
is converting the data from ascii to binary or what. He is a thinking human
being and will ask if he continues to have trouble and cannot sort it out
for himself.
to be mapped to some kind of color scheme, and second, how to display those colors. The first is a requirements or design decision on his part, the
second is simply off-topic here.

I don't see any question about displaying the data yet, so far it is
on-topic.