E-Ink Display shows image zoomed in

[zapp98]

Setup:
ESP32 WROOM 32 Devkit V1
Waveshare 4.2inch e-Paper Module rev2.2, b/w 4 gray with logic converter /added: Link to display
Waveshare demo library (Waveshare Download)
Waveshare demo library (github e-paper )

Software:
Photoshop to set the image size (400 x 300 pixels) and then convert to 4 gray scale
Image2lcd v3.2 to convert the image to c array and reverse the color for the display

Rightio guys, basically at the end of my tether with this one. Was hoping to make this as a gift for someone, however it's proved to be more challenging than I expected.

I have tried a number of library's to no avail, this includes the famous GxEPD library by @ZinggJM and I must say, the library and examples are written very well, however I have come to the conclusion that my revision of the display is not included, and so I have found that the demo from waveshare themselves seems to work to some extent. Documentation regarding commands and such seems to be lacking or I am just struggling to get my head around it.

My issue that I am coming up against is that when I generate my own bmp images and then convert them to c arrays, the image shows up zoomed in, however, when I use the images from the demo, there is no issues at all. so I am at a loss.

Any help is much appreciated! Thanks

Here is my code so far, it is basic, I am just trying to display an image at the moment...

/* Includes ------------------------------------------------------------------*/
#include "DEV_Config.h"
#include "EPD.h"
#include "GUI_Paint.h"
#include "imagedata.h"
#include <stdlib.h>

/* Entry point ----------------------------------------------------------------*/
void setup()
{
    printf("EPD_4IN2_V2_test Demo\r\n");
    DEV_Module_Init();

    printf("e-Paper Init and Clear...\r\n");
    EPD_4IN2_V2_Init();
    EPD_4IN2_V2_Clear();
    DEV_Delay_ms(500);

    //Create a new image cache
    UBYTE *BlackImage;
    /* you have to edit the startup_stm32fxxx.s file and set a big enough heap size */
    UWORD Imagesize = ((EPD_4IN2_V2_WIDTH % 8 == 0)? (EPD_4IN2_V2_WIDTH / 8 ): (EPD_4IN2_V2_WIDTH / 8 + 1)) * EPD_4IN2_V2_HEIGHT;
    if((BlackImage = (UBYTE *)malloc(Imagesize)) == NULL) {
        printf("Failed to apply for black memory...\r\n");
        while (1);
    }
    printf("Paint_NewImage\r\n");
    Paint_NewImage(BlackImage, EPD_4IN2_V2_WIDTH, EPD_4IN2_V2_HEIGHT, 0, WHITE);

#if 1  // show bmp
    // printf("show window BMP-----------------\r\n");
    Paint_SelectImage(BlackImage);
    Paint_Clear(WHITE);
    Paint_DrawBitMap(gImage_barb);
    Paint_DrawImage(gImage_barb, 0, 0, 400, 300); 
    EPD_4IN2_V2_Display(BlackImage);
    DEV_Delay_ms(2000);
    
#endif        

    // EPD_4IN2_V2_Init();
    // EPD_4IN2_V2_Clear();
    // printf("Goto Sleep...\r\n");
    EPD_4IN2_V2_Sleep();
    free(BlackImage);
    BlackImage = NULL;

}

Following on from this, here is the BMP image I am using as a placeholder for now, it will not allow me to upload the BMP so here is the original image.

This is the c array code after I have set the size to 400 x 300 and converted the image to 4 gray scale

barb.c (150.2 KB)

And finally what i see in the screen of the display

My Settings on Image2LCD v3.2

[toddnz]

Quick thought: try rotating the image. By default these sort of displays seem to be portrait, not landscape.

Alternatively, the library might allow you to set rotation somehow.

Edit: for future reference, this was an "off-the-cuff" response, and after a few moments of research I suspect that this is untrue and irrelevant for this display.

[zapp98]

I have made some progress... by adding the 4 lines after the first comment, it will now drawer about half the image on the display

#if 1  // show bmp
    // printf("show window BMP-----------------\r\n");
    EPD_4IN2_V2_Init_4Gray();
    Paint_SelectImage(BlackImage);
    DEV_Delay_ms(2000);
    Paint_Clear(WHITE);
    
    // Paint_DrawBitMap(gImage_barb); 
    Paint_DrawImage(gImage_barb, 0, 0, 400, 300); 
    EPD_4IN2_V2_Display_4Gray(BlackImage);
    // EPD_4IN2_V2_Display(BlackImage);
    DEV_Delay_ms(2000);
    
#endif    

@toddnz if i rotate it in photoshop and then tell the esp to rotate it again will it make a difference?

[zapp98]

Issue has been resolved. I don't understand if all this code is necessary, however it has the expected results now.

Good luck and have fun kids!

/* Includes ------------------------------------------------------------------*/
#include "DEV_Config.h"
#include "EPD.h"
#include "GUI_Paint.h"
#include "imagedata.h"
#include <stdlib.h>

/* Entry point ----------------------------------------------------------------*/
void setup()
{    
    printf("Beginning Setup------------------\r\n");
    DEV_Module_Init();      //Needs to be present
    EPD_4IN2_V2_Init();     //Needs to be present
    EPD_4IN2_V2_Clear();    //Needs to be present - Clears display on boot
    // DEV_Delay_ms(500);      //Needs to be present - Waits some time to let display chill


    //Setup the environment and catch errors
    UBYTE *BlackImage;
    UWORD Imagesize = ((EPD_4IN2_V2_WIDTH % 8 == 0)? (EPD_4IN2_V2_WIDTH / 8 ): (EPD_4IN2_V2_WIDTH / 8 + 1)) * EPD_4IN2_V2_HEIGHT;
    if((BlackImage = (UBYTE *)malloc(Imagesize)) == NULL) {
        printf("Failed to apply for black memory...\r\n");
        while (1);
    }
    //End Environment setup
    printf("Setup Complete-------------------\r\n");

    

#if 1

    printf("show Image-----------------------\r\n");
    EPD_4IN2_V2_Init_4Gray();
    free(BlackImage);
    BlackImage = NULL;
    Imagesize = ((EPD_4IN2_V2_WIDTH % 8 == 0)? (EPD_4IN2_V2_WIDTH / 4 ): (EPD_4IN2_V2_WIDTH / 4 + 1)) * EPD_4IN2_V2_HEIGHT;
    if((BlackImage = (UBYTE *)malloc(Imagesize)) == NULL) {
        printf("Failed to apply for black memory...\r\n");
        while (1);
    }
    Paint_NewImage(BlackImage, EPD_4IN2_V2_WIDTH, EPD_4IN2_V2_HEIGHT, 0, WHITE);
    Paint_SetScale(4);
    Paint_Clear(WHITE);
    EPD_4IN2_V2_Display_4Gray(BlackImage);
    DEV_Delay_ms(2000);

    Paint_Clear(WHITE);
    Paint_DrawBitMap(gImage_barb);
    EPD_4IN2_V2_Display_4Gray(BlackImage);
    DEV_Delay_ms(2000);

#endif

    // EPD_4IN2_V2_Init();
    // EPD_4IN2_V2_Clear();
    printf("Goto Sleep...\r\n");
    EPD_4IN2_V2_Sleep();
    free(BlackImage);
    BlackImage = NULL;

}

/* The main loop -------------------------------------------------------------*/
void loop()
{
  //
}

[toddnz]

@zapp98

Paint_SetScale(4);

Well spotted!

This seems to be key. Glancing at the Waveshare library code, it seems that GUI_Paint is storing the 4 shades of gray in one continuous array, rather than separating them. If Paint_SetScale() is not changed to 4 (from the default of 2), the BlackImage array is being filled twice as fast as it should, causing only half of the image to display.

[zapp98]

now that you explain it, it makes a lot of sense! glad this is solved now