Re: [Gnuplot-info] Short horizontal line become exaggerated in saved plots

[Rob S. <rob...@ut...>]

On 04/14/2015 02:44 PM, Hans-Bernhard Bröker wrote:
> Am 14.04.2015 um 01:40 schrieb Rob Sargent:
>> Hoping third times the charm, with this posting.  My first was rejected
>> as not-a-member, the second seems to have simply wafted away...
>>
>> I'm running gnuplot 4.2 patchlevel 6 on RHEL 6.6.
>
> Well, that version is old: 5.5 years.  So the first and foremost 
> suggestion must be: update to something at least remotely current, 
> like 4.6 pl 6, or even 5.0
>
 From where I sit, that's the release on RHEL. I do have rpm's for 4.6 
but I'm hesitant to rock the install boat for this utility. Call me 
chicken but several attempt to modernize RHEL 6 have been troublesome.
>> I draw a number of (usually quite short) lines 4pt thick throughout the
>> plot. In the interactive window these are so short they are often barely
>> visible (and that's a good thing). But they become exaggerated in the
>> (viewing of) the saved plot, using jpeg, png or gif.
>
> Well, what do you expect a discrete, pixel-based terminal to do? You 
> didn't even reveal how big you make those images...
I typically define the window as 1600x400 for the saved images. 
Interactively I do not specify a window geometry; simply stretch the 
window and play with regions using the right-click-drag.
>
>> each of them is plotted from a generated file of this form:
>>
>>      1    23057190    2.709457    0.000000    23057190
>>      1    24552835    2.709457    0.000000    24552835
>
> That's a line covering just 1/2000th of your x axis range.  That 
> leaves a normal-sized pixel image only one of two choices: display 
> nothing at all, or display at least one pixel.  Neither of which you 
> appear to want.  So what did you expect to happen?
Perhaps I expect too much.  The interactive viewer (x11) does a 
perfectly acceptable single pixel rendering.  I'm confused why in the 
saved images, in multiple formats, viewed by a variety of tools, these 
barely noticeable lines are puffed up. Oh and whether or not I can do 
anything about it - if it's a problem in the save-to-file action of 
gnuplot I will upgrade to 4.6 (maybe 5) if this is a known, and fixed, 
issue.

Thanks,
rjs