<div dir="ltr"><div>Hi,</div><div><br></div><div>I think I'll modify the pixels in the image....like: img(x,y) = 255;<br></div><div><br></div><div>If necessary I will also change some neighboured pixels to enlarge the "dot"-size.<br></div><div></div><div><br></div><div>I do not need them blue...this was just to demonstrate that</div><div><br></div><div> plot(x,y,'o') ( = white)<br></div><div><br></div><div>and</div><div><br></div><div> xfarc(x_arc,y_arc, w_arc,h_arc,0,360*64) (= blue)<br></div><div><br></div><div>do not always plot at the same location....even all coordinates are just simple integers.<br></div><div><br></div><div>So far I could see, this does not change, even if one changes the pixel_drawing_mode attribute.<br></div><div><br></div><div>Thanks for your ideas,</div><div>Philipp<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Am Do., 1. Okt. 2020 um 10:25 Uhr schrieb Antoine Monmayrant <<a href="mailto:antoine.monmayrant@laas.fr">antoine.monmayrant@laas.fr</a>>:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
On 01/10/2020 09:05, Dang Ngoc Chan, Christophe wrote:<br>
> Hello,<br>
><br>
>> De la part de P M<br>
>> Envoyé : mercredi 30 septembre 2020 16:50<br>
>><br>
>> exact dot-coordinates, drawn as filled circles.<br>
>> All pixel coordinates of such an area would have to have exactly one single pixel value.<br>
>> The resulting graphic right now is stored via: xs2bmp.<br>
>> [...]<br>
>> - It seems that the resulting pixels of the dot in the final image are not equally colored.<br>
> I suspect the following thing: pixels are squares, not dots.<br>
><br>
> So it may be that xs2bmp somehow inter-/extrapolate the colours.<br>
> You then have a "leak" between the coloured pixel and its neighbours.<br>
><br>
> You may try to draw squares of the exact size of the final pixel (e.g. 1/320 width and 1/200 height of the graphical window for a 320 × 200 raster picture).<br>
><br>
> You may also try some functions from the image processing toolboxes.<br>
Well, another approach would be to:<br>
- use Matplot to display your image as a matrix, let's say [0:255] range.<br>
- modify the data in the matrix to be displayed where you went to get <br>
your "dot": like your change your data to 256<br>
- use a colormap that is grayscale from [0:255] and has a fancy color <br>
for 256 (blue?).<br>
<br>
If you do this, you should get a perfect co-registration of your image <br>
and your "overlayed" markers.<br>
Of course, your markers will not be circular dots, just a single pixel <br>
with what I described above, but you can also generate your own shapes <br>
(bigger squares, crosses, ~circles), provided that you use an odd number <br>
of pixels.<br>
<br>
Hope it helps,<br>
<br>
Antoine<br>
<br>
><br>
> Hope this helps<br>
><br>
> Regards<br>
><br>
> --<br>
> Christophe Dang Ngoc Chan<br>
> <a href="mailto:cdang@wanadoo.fr" target="_blank">cdang@wanadoo.fr</a><br>
><br>
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</blockquote></div>