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Topic: Nextion 7" display distortion (Read 190 times) previous topic - next topic

Gra55y



After transferring a .jpg background image to my NX8048T070_011 7" display via TFT file I get distortion of the image.  You can see the original 480x800 image in my photo editor and what it looks like on the display.  The X axis seems to be squeezed together, giving the circles an egg shape.  Is there a way to correct this?

Gra55y



180x180 pixels on my monitor is looks similar to 180x195 pixels on the Nextion.

Paul__B

You will need to superimpose a grid pattern specifying an exact number of pixel spacing, over your circles.

If in fact, the display pixels are slightly rectangular, there is not a great deal you can do.  :smiley-roll:

david_prentice

Draw a 800x480 rectangle.   Measure the dimensions with a ruler.

Most TFTs have pixels in accurate square matrix.   Remember that each "color pixel" is actually 3 individual RGB.    Examine with a loupe.

As Paul said,  just live with it.
Otherwise you will have to find another Nextion-compatible display.

You can use PC software to process images e.g. stretch in one direction.

David.

PerryBebbington

I have measured as accurately as I can the viewable area of a 7" CPT Nextion display and find it to be 152.89mm by 85.09mm. 152.89 / 85.09 = 1.7968.
800 / 480 = 1.6669
I don't know if that difference in ratio is enough to notice or if it is just due to the inaccuracy in my measurements.

david_prentice

#5
Aug 24, 2019, 10:16 pm Last Edit: Aug 24, 2019, 10:27 pm by david_prentice
800/480 = 1.667

So it really is not very accurate.   It is 8% wrong.

My 5 inch SSD1963 is 109mm x 66mm i.e. 1.65 measured with a ruler on a non-powered display.

Since these items are manufactured with accurate machinery,  photo plates I would expect "perfect accuracy".

David.



Paul__B

#6
Aug 24, 2019, 11:20 pm Last Edit: Aug 24, 2019, 11:39 pm by Paul__B
Most TFTs have pixels in accurate square matrix.
So that was just an unsubstantiated assertion - or guess.  :smiley-roll:

Remember that each "color pixel" is actually 3 individual RGB.    Examine with a loupe.
Which means that each colour stripe must be three times as (?)high as it is wide as it is (?)wide - or more than that to allow for the spacing between.  Or else a hexagonal "tile" in a tessellated pattern, like the original shadow-mask TVs which for engineering reasons switched over to the "Trinitron" pattern of vertical stripes which is what I presume these LCDs use.

It would seem you are lucky it is so close to a "square" pixel.  :smiley-lol:

david_prentice

So that was just an unsubstantiated assertion - or guess.  :smiley-roll:
Which means that each colour stripe must be three times as (?)high as it is wide as it is (?)wide - or more than that to allow for the spacing between.  Or else a hexagonal "tile" in a tessellated pattern, like the original shadow-mask TVs which for engineering reasons switched over to the "Trinitron" pattern of vertical stripes which is what I presume these LCDs use.

It would seem you are lucky it is so close to a "square" pixel.  :smiley-lol:
Yes.   It is an unsubstantiated assertion.    I had never noticed "distortion" on any of the TFTs that are on my desk.
I can't claim anything for displays that I have not seen.   I can only believe Mr Bebbington and Mr Gra55y.    I do not have the Nextion.

Yes.   My TFTs are all Trinitron-style.    i.e. RGB rectangles in a horizontal row.
Most of my TFTs are Portrait e.g. 240x320
My SSD1963 display is Landscape e.g. 800x480

Of course you can display graphics and text in any direction that you want from GRAM.   But the controller will scan the RGB pixels in the natural row direction.

David.

TFTLCDCyg

#8
Aug 25, 2019, 04:36 am Last Edit: Aug 25, 2019, 04:38 am by TFTLCDCyg
Most of the screens of 7" that I have been able to get, have rectangular RGB matrices, not square ones. Up to 5", the dimensions are closer to the square arrangement.

NHD FT813 7" 800x480


Riverdi FT813 5" 800x480


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