A widget that shows the current image thumbnail instead of clear/modify controls.

main.js

function styleFileUploader(fileInputId) {
    var fileInput = $(fileInputId),
        addFileField = fileInput.siblings('button');

    fileInput.hide();

    addFileField.on('click touchstart', function (e) {
        fileInput.trigger('click').trigger('touchstart');
    });

    fileInput.on('change', function (e) {
        var input = $(this),
            reader = new FileReader();

        reader.onload = function (e) {
            addFileField.css('background-image', 'url(' + e.target.result + ')')
                        .addClass('loaded');
        };

        reader.readAsDataURL(this.files[0]);
    });
}

styleFileUploader('#id_photo', true);

widgets.py

from django.utils.safestring import mark_safe
from django.forms.widgets import FileInput
from django.conf import settings


class ThumbnailImageWidget(FileInput):
    """
    A FileField Widget that displays an image instead of a file path
    if the current file is an image.
    """
    def render(self, name, value, attrs=None):
        output = []
        file_name = str(value)
        file_thumb = '''
            <button type="button" class="upload-photo loaded" style="background-image:url({})">
                <span>+ Carregar imagem</span>
            </button>
        '''

        if file_name:
            file_path = '{}{}'.format(settings.MEDIA_URL, file_name)
            output.append(file_thumb.format(file_path))
        else:
            output.append(file_thumb.format(''))

        output.append(super().render(name, value, attrs))
        return mark_safe(''.join(output))