[TYPO3-core] RFC #11177: Feature: New options noRescale and resolutionFactor for getImgResource()

[Franz Koch]

Hi,
>>>> sorry, I like the general idea, but I don't like the way it's done. 
>>>> The "resolutionFactor" is somewhat odd to me. For me it would make 
>>>> much more sense to actually define the dpi (Dots Per Inch), so that 
>>>> based on the given width and height and the dpi you can calculate 
>>>> the total dimensions (default for screen are 72dpi).  
>>>
>>> OK: I will change that.
>>> Is the screen-resoution always 72dpi (in this case) or should I use 
>>> the settings in localconf $TYPO3_CONF_VARS['GFX']['TTFdpi'] ?
>>
>> screen resolution is afaik always 72dpi - and even if not it would 
>> depend on the output device that you can't control. All images for the 
>> web are generated with 72dpi.
>>
> 
> and why do i have to set it to 96 always to get the right test image? 
> setting of 72 will double the text for me always (in all installations)

Fontsizes are a different thing. In this case 96dpi is the scaling 
factor for the font (this is also the default scaling factor in windows 
and on mac afaik).

Dealing with dpi is really no fun - a lot of people never understand 
what dpi actually means. DPI don't tell anything about the 
size/dimensions of a image or a font, they only define the "scaling 
factor" that should be used by the output device (if supported). The 
dimensions are always pixels (in the digital world). So a image with 
800x600px will always be 800x600px, independent of the dpi defined. And 
on the screen you won't see any difference if you change the dpi as 1 
pixel of the image is 1 pixel on the screen (unless your graphics 
program is supporting those and simulating it).
DPI means "dots per inch" or in the digital world "pixel per inch" and 
is mostly used to define the desired resolution (don't mix it up with 
screen resolutions) that should be used when printed. So, having a image 
with 300x300px set to 300dpi (300 dots/pixels per inch) means that 300 
pixels will be printed over the length of one inch. So this image will 
be exactly 1x1 inch when printed and look quite sharp. If you set the 
dpi to 100dpi, the printed image will be 3x3 inch and look blurry (you 
can count every pixel). So, the higher the dpi, the sharper the image 
when printed, but also the smaller the image.

-- 
kind regards,
Franz Koch

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