pset4 ./resize .2 (.4)

Question

I'm done with resize [more]. And check50 was ok. But when i check my program for not 0.25/0.5 size, but for size 0.2/0.4 the image was fail ./resize .2 large.bmp student.bmp

• .1 - OK .15 - OK
• .2 - err .25 - OK
• .3 - err .35 - err
• .4 - err .45 - err
• .5 - OK .55 - err
• .6 - err .65 - err
• .7 - err .75 - OK
• .8 - err .85 - err
• .9 - err .95 - err

I tried to change (int)(bi.biWidth * f) to (int)round(bi.biWidth * f) and/or (out_bi.biWidth * sizeof(RGBTRIPLE)) to ((int)round(out_bi.biWidth * sizeof(RGBTRIPLE))) but it does not help.

I tried to use ceil floor, but it does not help.

Anyone have idea how to fix it?

my code

EDIT:

For example 0.75 vs 0.70

int row = 0;
int col = 0;

row += abs(out_bi.biHeight);
while (row > 1)
col += out_bi.biWidth;
while (col > 1)
col-=bi.biWidth;
row-=abs(bi.biHeight);

I tried to change row and col before 'cycle' and change it in 'while' but it does not help. I miss something, but i don't know what.

Answer 1

f < 0 && f > 100 should be f <= 0 || f > 100. Not your current problem, though.

In my solution, which is very similar, I avoid floating point. First, I calculate round(bi.biWidth * f) and so on (no differentiation between scaling up or down), from then I only work with the old and new width and height, which are integers. Adding new size before the while loop, subtracting old size in the loop. That way, my bitmap is always consistent with the image dimensions, no further rounding errors possible.